How about Obsydian? Seems like a great and flexible app, plugins to add as much as you like, and free for personal use.

Not sure about the zero, but seems to be ran successfully on other raspberries, see https://forums.raspberrypi.com/viewtopic.php?t=344018

I don’t run Linux , but I love Prusaslicer and it is available for Linux: https://flathub.org/apps/com.prusa3d.PrusaSlicer

How do you track (PostNL) packages?