I have an ancient Pixel 3 that still works. I'd like to install a new, third-party OS. Which would you recommend?
I can see that there are many: Lineage, Calyx, /e/, Graphene, .... How do I make the decision? Can all of them work on a phone as old as my Pixel 3?
Edit: holy shit, I just installed Lineage OS on my lunch break! I've installed "alternative" OSes before on computers but never on a phone. I just followed the instructions (which were a little confusing as there were nested steps) and it's up and running!
I think the decision is already made for you. Only lineage OS still supports the Pixel 3
The other operating systems you mention are security focused, so a phone without any security updates or driver updates is not something they can operate on in good faith.
Crdroid (which claims performance improvements, but also has a lot of customization options; reminds me of now deceased resurrection remix) is also good but doesn't seem to officially support your device. There may be some ports on XDA, tho.