the files there are static and will not change mostly on updates… but as it says in the link Arch is not Suse and Arch Grub is not the same as Suse Grub.
btrfs.mod - This module provides support for the B-tree Filesystem.
so if the needed support module for the filesystem is on a subvol it looks legit for me that grub can not read it ?
I know this might not be directly helpful but i found this guide being very easy to follow regarding setting up btrfs snapshot volumes on Arch during install, it’s the one i used for the install I am running at the moment and has for a month and a half with no issues:
This is an excellent tutorial. I’m going to reinstall Arch and set it up this way on Plasma. 
One of the few Linux tubers I still follow, and follow closely.
(Also, I did alter it a bit, I use Timeshift for the snapshots instead of using a snapshot volume).
Well all i can say is I’m not going to learn this from the Arch wiki alone. It’s just too difficult to browse through all the technical info and put it all together in a way I can understand by just reading it. I can’t always just read information and have my brain organize it and automatically know how it has to be done. Being shown with some explanation is much more intuitive. Even so i can do it but not necessarily understand everything. But, it’s enough to get me where i want to go. That’s a satisfying feeling to be able to accomplish what i want to without being totally defeated. 
What I did was to watch the video twice and take notes, then open the arch wiki on my phone while installing as a backup.
Sorted on the first try, about 25 minutes.
(Compare to my first arch install exactly three years ago that took 6 hours 
).
Exactly … my first Arch install probably was the same or longer. Now i can do it pretty quickly but i still need notes to follow where I’m going or I’ll trip! 
There’s just so much too it and every desktop environment is different. Plasma is very easy. I would say I’m content with where I’m at as far as knowing what I’m doing but never content with how much I don’t know. It’s ongoing …
Yes, he is pretty good. By the way, do you really need Timeshift, I mean does the Arch install die in time? I have a feeling that it doesn’t.
It wont die on its own, only if you fiddle too much like I do.
I like fiddling… 
It’s just a good-to-have thing. I have that, and keep the pacman cache empty instead.
You really don’t need both snapshots AND a pacman cache really.
i would simply use calamares to try out a BTRFS setup and then add snapshot addition:
Nice… Now how do you add snapshot addition? Snapshot & Timeshift are two separate things correct?
Well yes and no. If you configure snapshots within BTRFS like the tutorial I linked to you do not need Timeshift.
However, you can also just ignore the snapshot subvolume and configuring snapshots at setup completely, and just install Timeshift and choose “BTRFS” in the first-run setup wizard. Providing you have room on your / partition for snapshots, of course but if you plan to use snapshots you should.
Edit: Remember that if you use Timeshift with btrfs as the option you cannot have a separate /home partition. Even if you chose to not back up your /home.
I solved that by having an external 4TB drive I house media files (aka movies) on and that I also back up my images and documents to.
Edit again: I chose this because it is a clean visual GUI display of all current snapshots and free disk space. If anyone is curious I run 1 weekly, 5 daily, 3 hourly and 3 boot snapshots.
I can follow the tutorial and it’s great. I was just asking as it said at the top of the video add snapshot addition. Not sure what is involved after following joes video.
You are right. It is having /boot/grub/x86_64-efi on a separate subvolume that doesn’t give EndeavourOS to boot.
I copied all files from x86_64-efi subvolume into x86_64-efi folder in the / subvolume, and uncommented x86_64-efi subvolume entry in fstab. And BAM! Now, I am able to boot.
OpenSUSE probably uses its own patches that makes it possible to create /boot/grub/x86_64-efi subvolume.