I use zotero with logseq and synchronize everything between my devices using syncthing. It’s all pretty easy to set up with little research, I think.

Logseq has a good integration with zotero and lets you annotate pdfs directly in it (although the notes stay in logseq, not on the Pdf). It’s also good to link themes and topics with certain papers (e.g., papers on accessibility). I find it pretty easy to find papers like that.

Some plugins help “make it yours”. But I can’t link to them now.