If you drop the plaintext requirement (which IMO is anachronistic, if not for the necessity to fend against a potentially turning hostile developer in a close-source set-up), you may find https://triliumnotes.org/ liberating.

If you must stick to the "notes as plain text files" paradigm, siyuan is better than obsidian in about every aspect, and logseq in other, more niche ones. Trilium is better than them all (IMHO), being the only one that does "note as data" correctly and efficiently (you don't have the same data model divide like seen in notion between notes and databases).

https://joplinapp.org/

Seems interesting

Im a VSCodium kind of guy myself

The silence is deafening, because there isn’t a FOSS program that comes close to Obsidian’s functionality. This isn’t the first time I’ve seen someone drop the “lul just use FOSS instead” line to garner upvotes, when literally no FOSS alternative exists. There are some FOSS programs that come close in some regards, but none of them do everything Obsidian does and support multiple platforms.

Lemmy has an obsession with FOSS (for good reason) but that means many users basically try to act like FOSS vegans. They’d use six different (and largely incompatible) FOSS programs just to scratch the surface of what a closed-source program can do. And their hackles start to raise if you ever point out that there aren’t FOSS alternatives for everything.

Since it's a topic that comes back often on /c/selfhosted@lemmy.world I didn't want to open new floodgates, but I can only warmly recommend https://triliumnotes.org/ :-)