After playing around with systemd-boot for a long time, I decided to go back to grub. Everything works, except that the boot entries are showing “Arch Linux” instead of “Endeavour OS”. Is there a package I need to install to fix this, or is there a simple grub config that I missed?
One of these might be helpful:
Modifying the GRUB_DISTRIBUTOR line on /etc/default/grub
Modifying /etc/lsb-release file
Modifying /ets/os-release file
Look for “Arch Linux” in these files and change them to EndeavourOS.
Back them up if you are not sure what exactly you are doing.
The release files are fine. The GRUB_DISTRIBUTOR line shows “Arch”; somehow when I update grub it adds “Linux” to the title. I changed the aforementioned line so I at least get “EndeavourOS Linux”.
Reinstall eos-hooks package, I think that should take care of everything.
sudo pacman -S eos-hooks
Typically, you should not need to modify the lsb-release and os-release files manually.
I may have nuked that package when I first removed grub. I’ll give it a try after I kill Diablo. 
EDIT: it didn’t help. I can’t remember what it showed after my initial install as I switched to systemd-boot right away. I know where the hooks are now, so I can make the edits I want.
Thanks again to all that replied.