Hope you find something that works! I do enjoy that Joplin is not paywalled in anyway, and is still super robust, private, and local first. I personally hop around between several note taking apps based on my needs so finding apps that are local md first is high priority for me so that if I move to another app all of my notes can move with me.
Joplin stores notes in a database rather than directly as Markdown, but they can easily be exported as Markdown which I guess is the next best thing.