If you want work alongside people experimenting with rejuvenation therapy, Calico labs works on that. They hire in-house software people and also of course use software provided by external companies.

I haven't worked for them or with them directly, so I don't know anything else about it, but it might be one place to look. I'm sure there are others; they must have competition.

Something that doesn't exist? You build it.

Something that you know of you check similiar companies.

If you are just browsing for ideas visit angelist.

If you want a great job you have to search. If you don't want to search you'll apply to places you know like big tech.

Another piece of advice is to get involved outside of work and you will be first to hear about the interesting positions.