If the project is still valid with a community of users some development can be supported and even if you are alone without programming skills you can still pay a developer to fix bugs or implement features that are important to you.
I remember Kdenlive video editor was almost dead for years, then suddenly someone started to contribute again, it grew a lot and now it's one of the best FOSS video editors.
About Obsidian's Markdown, yeah you can stick to standard syntax but it seems to me Obsidian enthusiasts are too much confident that "it's just plain text" but then they found out themselves tied to 20+ plugins for their UI/UX, not because of how data is stored.
Same it's true with Logseq that introduces its own special syntax, but at least it's FOSS.
