Hello. I’m a Debian user looking to move to using EndeavourOS on a new system in the coming weeks. I’ve been reading through the Arch Wiki, among other things, in an attempt to start familiarizing myself with an Arch-based system.
My question is, how many packages from the AUR are installed on EOS in a default install? Will I need to use yay -Syu for updating my system, or will I be able to use pacman -Syu? I have to ask, because I’d prefer to avoid using the AUR on my EOS install.
yes. you can also update via yay.
Any AUR packages that EndeavourOS uses have been added to the EndeavourOS repository. So yes.
BTM we do not use AUR per default, there is no package that needs yay or rebuilds from AUR, we adapt some packages directly from AUR, but they can be installed over the EndeavourOS repository 
Welcome at the purple side of linux! 
Ah, Endeavour maintains its own repository? That’s good to know, thank you.
Since you’re not on an Arch-based system (yet!), I’m going to assume a few things. I’m sure you’ve done your own research, but just in case you haven’t come across it yet, I’d like to mention a few things. You can use pacman -Syu OR yay -Syu to update your system, either is technically fine. Pacman will only update packages in the Arch/EndeavourOS repos and Yay will update packages in the aforementioned repos as well as check the AUR for any package updates. Yay is installed by default and is maintained in the EndeavourOS repos and contrary to any misinformation out there Yay is still actively maintained by the developer. Another little thing to note, running the command yay is an alias to yay -Syu which does the same thing, so to save time updating, you can simply just run yay and not have to include -Syu every time. Neat, huh? Hopefully I didn’t confuse you on that one!
You’re not required in anyway to ever use the AUR. but the AUR is nothing to be afraid of. A lot of packages that are in the Arch and EndeavourOS repos did once start out as an AUR package, so whatever your reason(s) for not using the AUR are, please just keep in mind that the AUR can be a great place to find and discover additional software, that can be extremely useful to some users. As long as a user is knowledgeable enough in using the AUR, it is safe to use. At the end of the day, it’s your system, so please free feel to use it however you wish, I simply wanted to offer some information I would’ve found helpful when I first started out on my journey into an Arch-based system. I hope this was helpful as well 
Thank you for the detailed reply, although I admit you did confuse me on that last bit of your first paragraph.
Assuming I understand what you said right, rather than run “yay -Syu” (or pacman -Syu) in the terminal, I can instead run “pacman yay” since yay is an alias for “yay -Syu”?
If you were to run pacman yay you’d get this:
[scott@endeavourOS ~]$ pacman yay
error: no operation specified (use -h for help)
[scott@endeavourOS ~]$
This is just to show you that that is not an actual command that works with pacman. It’s good to learn through things like this. If you haven’t come across it already, there is a Pacman commands list comparison with Apt that is very useful and quick to look at to get a feel for what commands you can use with Pacman: Pacman Rosetta Guide
Pacman doesn’t know what to do with yay, it’s not an operation that is a part of pacman. Pacman is the Arch package manager (Apt is the Debian package manager), and Yay is like an “add-on” that functions just like pacman, but is separate from it, that also include the ability to use the AUR.
For a quick introduction to Yay, check out the developers readme to see some of the commands you can use with Yay here: Yay Github
To break it down as simply as I understand it to update your system:
pacman -Syu - updates Arch/EndeavourOS repos
yay -Syu - updates Arch/EndeavourOS repos AND AUR
yay - updates Arch/EndeavourOS repos AND AUR
The last two do the exact same thing, I just was trying my best to mention that yay is an alias for yay -Syu which means that when you run yay is it essentially running yay -Syu so you don’t technically need to write yay -Syu since yay will do the same. Just keep in mind, if you don’t ever use or need any AUR packages, then you can safely and happily use pacman -Syu to update your system. Hopefully that clears up any little confusion I might have caused 
Oh, okay, so you meant yay can be used itself rather than needing to add -Syu at the end.
I had’t seen that Rosetta guide on the Arch Wiki yet, but it’s just what I need. Thank you for the information.
No worries, happy to help and that Rosetta guide is a great resource to read before taking the plunge into an Arch-based system. Also don’t forget to check out the EndeavourOS wiki section which also has a wealth of useful information specific to this lovely distro of course:
Zero. Exactly the way it should be.
Just thought I’d give a small update and mention that I’ve since finished my PC and have been running EndeavourOS on it for almost a week now. It’s been very pleasant to use. Frankly, I’m surprised how smooth the transition was from Debian to an Arch-based system.
The only real sore points I’ve encountered have been with Steam, and not Endeavour itself. The first one I managed to solve, but the second one is just general quirks with Proton. A few games that ran fine on Proton in Debian don’t in an Arch-based environment. Also, the Steam Flatpak is apparently unable to launch games with Wayland; didn’t know that. I was going to use that, but am back to using the Steam runtime in the Arch repositories.
Something to note, Wayland will eventually replace Xorg at some point in the future for most distributions (it’s already a default in Fedora). It’s in a good state, but Wayland is still not yet production ready for every single piece of hardware out there and use case. Xorg is still my default and probably will be for at least another year. Gaming on Linux is insanely better than it was just a decade ago, but for some things it can still be a hit or miss, so expect issues from time to time. If gaming is crucial to you, it never hurts to have a Windows partition setup just as a backup. Other than that though, glad you’re having a great time on EndeavourOS, hope it continues to be an enjoyable experience
Gaming is crucial to me, but I also hate Microsoft and haven’t had Windows on any computer I own since August of last year. Proton can be finicky sometimes, but for the most part, every game I’ve wanted to play (on Steam) I’ve been able to play. Frankly, I’m just grateful I can play games without using Windows at all.
I am also in the (slow) process of migrating various computers from Debian-based (Kubuntu) installs to EOS, and I just wanted to say thanks for that link. I don’t find pacman’s man page super user-friendly, and this looks like exactly what I needed.
I guess the takeaway is that the wiki is a great resource and I should really use it more, because Rosetta is prominently advertised at the beginning of pacman’s page…