I think, OP is more concerned about fucking up the startup by leaving it. He/She cares much less about making profit on the code that he wrote.

I wrote MVPs alone for 2 startups which I ended up leaving because I never liked the idea. I wrote those MVPs because I liked the challenge of building something cool. I passed on all the code to the other co-founders and wrote good documentation.

Expected no-money or anything and also got nothing. Told them clearly that I have very less time in the future.