That's kind of what I've done. I looked around some last year, didn't see much out there, had a few interviews here and there that usually ended in ghosting. After the unemployment ran out stopped looking for a while. Then started looking again recently because I'm not sure I'm ready to be retired yet.
There are volunteer or more-or-less volunteer things you can do but you need to find the right open source project (or start one), find a channel where people will actually read what you write and do it regularly enough, have connections to people who actually want your advice, etc. Once you're not connected to an organization some of those things are harder than they seem unless you have specific, still-relevant credentials.
