Distrobox also works with GUI applications. Toolbox, probably too

I'm trying to solve problem with coding in NixOS with Distrobox and Archlinux container with all the tools for development. Work fine for me.

Take a look at the GNU Guix System. It's similar to NixOS, but maybe their configuration language will be easier.

Confirmation on what? Togashi still works on it, considering his possibilities due to health (his twitter). Manga just won't be serialized weekly anymore.

Hunter x Hunter isn't cancelled.

I recommend watching JJK0 after the current arc. Events in the movie will make more sense and will be relevant later.