Fish is a surprisingly good shell.
It’s not POSIX compatible, but I don’t really care, it only executes its own scripts / functions. It’s not as innovative as elvish or nu, but it kind of does everything very conveniently and shell-y for lack of a better word – and it always seems so simple. It seems conservative in design, but the old concepts have been evolved in a very usable way. Something I can’t say for all the other shells I’ve tried – at some point, it always gets awkward where fish is just elegant.
I have opened a pull request at https://github.com/NixOS/nixpkgs/pull/367042, there might be more changes needed as I had an error in the meta section of the package which I rectified according to the reviewers proposed changes. Not sure this is the end of it, but the request is open