Yeh, venting on the internet helps. And it's always great when you actually connect with someone.

I always wish I'd learned a trade. Electrician, plumber or tiler. Get an apprenticeship, learn a trade, be a sole trader, do something physical that's always in demand.
Plenty out there to do, and it's ok to mourn your last job (being a student/doctorate is a job).
Connect with old friends and family. Meet some new people. Somebody will be looking for someone smart and compassionate

You mentioned space science, right? I’m an engineer at an aerospace company, feel free to message me if you want to chat about the industry, I’d love to help if I can.