Hi,
I wanted to share my dual boot with shared partition setup cause it took me some trial and error iteration to “achieve” (and a few hours because of windows reinstall).
Hardware: ROG Ally X + 4tb
First I tried the “recommended” way (at least was presented as so) with windows minimal partitions and a big bazzite btrfs volumes set (mounted with winbtrfs).
It worked some time (not long) till big crash on GOWR and no more boot at all…
And I didn’t liked the fact that winbtrf was mounting and viewing all the sensitive Linux files. I felt naked lol.
So tried something else.
I created the minimal partitions for windows and a minimal btrfs partition set for bazzite and a big shared NTFS partition in between (called it DMZ).
Do not forget to add nofail in your fstab… You have to deactivate the quick boot from windows. Used ntfs3 mount type and add option the handle case sensitive names, uid, gid, etc.
It’s working but sometimes you have to repair the NTFS partition from windows or partition won’t show in bazzite… And it was laggy under bazzite…
So tried something else… Again.
I turned the shared partition to ext4 and installed ext2fsd (the newer ext4 fork). You have to mount ext4 with uid 1000 and gid 1000 (you can set it up with ext2 manager under windows). You may have to chown -R your mount point the first time. Under windows you have to enable the WebClient service or elevated executable won’t launch (do not ask, found this hack on the winbtrfs git after a few hours).
So know it kinda works for the best. Sometimes windows cannot close the explorer and ask to close the explorer before a restart.
But bazzite side seams a lot safer because windows cannot access Linux stuff at all.
So far so good 
I can share my steam folder seamlessly and switch between windows and linux.
Thx for reading