Since you've got self-funded Basic Income, do what all those Basic Income people say people will do :P
I've had plenty of software engineering jobs that were interesting and 9-5, both at small companies and large. That was important to me, so I would always ask expectation of hours during the interview. So I'd say most of the options still exist. (This was in Austin, though, not SF)
You could try contract work, for example with Toptal. If you go the small projects route you get to work on all kinds of different things, and you can take a break in-between if you want. There's also long-term full-time contracts, and even some long-term half-time ones. This might be a good option if you want to explore, or if you are a generalist, or you want flexibility. It's also an opportunity to get a new perspective on work: what is it you are really selling? For contracting, two things you are selling is "I will solve your problem" and secondarily you are also selling flexibility to the buyer (ready to be done with the contract tomorrow, boss? Great, it was a pleasure working with you, let me know if you need anything in the future).