Running your own private discount web hosting used to be fun and lucrative, less so with AWS nowadays and it takes time to build up a customer base. Still fun though.

Short term project contracting is what got me out of my burnout. As did learning music on the side and just treating work like a day job rather than a calling.

You can also probably speak to some recruitment consultants about pitching you to companies as part time. So much work going one is bound to be happy with that.