I really want to use Obsidian but it being closed source is a big No for me. I know I can keep all my files in plain text and move on to another platform buy the thing is: if a bunch of files and a FS were enough for me to keep my KB, then ofc I wouldn’t need something like Obsidian. The thing is I need something like Obsidian; a bunch of files lying around is not enough for me
Technically, Obsidian is just a fancy 'browser/editor' for markdown files laying around. Should Obsidian disappear as a functional tool tomorrow, recreating the basic functionality (show, edit, manage links, follow links) would take a sufficiently motivated guy a few hours. If you need the 'petri dish' view, maybe a little longer. In such an event, I suppose enough people would be eager to build their own and OSS variants would emerge within days.
If you can stomach not working in Markdown, emacs' ORGmode exists and has all the functionality Obsidian has, and then some, open source, with a slightly different hypertext format.
Unless you are hellbent on one particular Obsidian plugin, you should be good.
What risk are you trying to avoid? You can disable updates.