There might have been some delayed writes on Arch, but that's no the main issue.
When booting into Fedora and running an update, the state of the filesystem changed to the point that when resuming Arch, it put the filesystem into an extremely inconsistent state (where the Arch system might have cached (meta)data that was changed since hibernation).
Also, to clarify, I still managed to recover my data, but the FS was not mountable and btrfsck couldn't do shit.
And I'm still using that Arch install to this day. XDDD
Hibernating my computer and then forgetting about it and booting into a different OS (Fedora Silverblue) on the same partition (BTRFS subvolume stuff). AND THEN TRYING TO RESUME THE HIBERNATED OS (Arch btw).
my filesystem was pretty much unrecoverable and it was my fault
Pretty much. I do have some releases, but considering Nix's philosophy you probably should.
Ventoy-CPIO should build fine, if the right toolchains and dietlibc are in PATH.
Ventoy-boot relies on overlay mounts though, so it might not build within Nix.
On Linux installation is done through a series of scripts and vtoycli. I haven't worked on that yet, but there's build scripts there that should do the trick, but since they build it for multiple architectures, you'll have to run just the stuff for your arch (probably x86_64).
TLDR: There's binaries instead of source code in the repo, which makes it hard to near-impossible to verify what it's doing. And the instructions for building those is lacking.
You wouldn't be surprised :3