I liked (and used) logseq for a while (since I could easily relate to the idea of outliner). But their development stalled; now they have moved to db based structure.

I am less concerned about open source than open standard. I have had my notes in text, jpg for more than a decade. Have used plain text editors (textmate?), nvALT etc and now use obsidian. I am sure these text files can stay for another 10 years even if obsidian itself goes out of business.

It's an open source software but I think we have to start restricting the definition of FOSS to remove software that have a requirement for continuous to sign a CLA and the organization is VC funded.