You could do contract / freelance work. You’d have to pay healthcare yourself.

Part time? Like, really actually part time? Once you factor in all the time finding paying clients?

YMMV, but when I was a consultant (which was great in my twenties, I worked three days a week) I mostly partnered with local consultancies who needed specialists in particular fields for this or that. A little staff aug in there too, but again for specialty stuff. They took about a 30% vig all-in-all off the top and they kept me full-up on work as much as I'd wanted.

Probably not. I've had some projects that went on for months, about 20 hours/week. Not recently though.