Free and Open Source Software

I'm currently paying a moderate amount to atlassian to host jira for me, and I'm looking for a FOSS way to replace it. I don't use it every month and I've decided it's not worth continuing to pay, plus I want to transition to FOSS wherever I can. I just feel trapped. I'm sure people here know the feeling when using proprietary stuff.

I've used hosted bugzilla before, and possibly I didn't know enough about how to make it work, but the web frontend they had was garbage, it was unintuitive and took forever to respond, and I just transitioned to jira because it was easier to use.

I'm happy to self-host for now and maybe pay for hosting if I want to collaborate in the future. I have a Ubuntu server at home with miles of headroom to run a webserver.

I would love to hear anyone's opinions here. Also any other relevant lemmy subs would be very welcome.

Edit: some good questions about my requirements. I'm doing software development on personal projects using git, and I'm tracking issues using jira. I'm also developing hardware, which means 3d print files, CNC files and possibly gerbers for PCBs. All this can be tracked via git, so actually having an in-house way to host all that would be great too.

So I need an issue tracker that syncs with git, essentially.

I have also been using jira to kind of ad-hoc document any research involved in these things, but it's not great because to find any of that documentation I need to dig into my closed issues. I'd like a documentation system that can handle diagrams, drawings and stuff like that, and if this could double as a general note-taking solution I'd love that too, because I've been trying to replace trello/onenote for that.

EDIT 2: Thanks for all the replies. I plan to investigate all the suggestions, my health has just been really bad since I posted this, but I always try to update anyone who offers help.