Some feedback, as I'm trying it out:
* I love that there's a .deb. Usually it's either a GH binary, or curlbash.
* I love the uninstallation instructions. Everyone else doesn't give a shit what they leave all over my filesystem.
* I can't really install it because I don't have Nix, and I don't really know how to get Nix on Ubuntu. I tried some packages once, but they didn't work. I'd appreciate some help here, as Flox is a non-starter if people can't install Nix. It doesn't even mention that I need Nix, the deb just fails to install. This is a pretty big omission.
EDIT: Turns out it fails because I already had Nix? The systemd unit needed to be removed. That's odd.
* I tried to follow the "first environment example", immediately got an error:
error: could not set permissions on '/nix/var/nix/gcroots/per-user' to 755: Operation not permitted
No guidance on how to proceed from here. That directory is already 755. Googling the error leads me to a GitHub issue with hundreds of comments, and no obvious solution other than somehow reinstalling, but I don't think I installed Nix in the first place?
That's the end of the line for me, sadly.