I had written a script to manage my pdf literature using crossref and arxiv to fetch metadata and store them in pdf tags, and just renaming the pdf in place. No hidden complexity, no gui.

I hacked it into a python package a couple of months ago in an ADHD hyperfocus induced frenzy. Sounds like you might like it. Still a long way to go, but it's out there and FOSS. Contributions are welcome.

https://github.com/jayghoshter/prem