Cmdchallenge is similar to Linux survival. But is mostly command line basics like moving around directories, searching, etc. It also gives a list of solutions that people have used for each exercise, which is interesting just to see different ways of doing things.

If you have libreOffice installed I believe you can edit pdfs in Draw.

You can also try Inkscape.

There is also a rust book that walks through building a todo app with rust and gtk (gnome desktop). Haven’t gone through it yet myself, but might be something you’d be interested in skimming through.