for every developer working on Go there are 1000 working on the most banal corporate crap you can imagine.
I'm not saying its a bad tradeoff - plenty of money. but if you care about what you do with your time, it might not be for you.
Another way to do it is to ignore the official process and go make friends on teams you're interested in. If you're looking for Go jobs, maybe just do a code search and figure out who's writing a ton of Go, and see if any of those look like fun. I know there's a lot of Go code in Cloud, which is usually hiring. There's some Rust in Chrome and Chrome OS, if you're into that.
I've never done a 20% project myself, but I hear those are good too. I gather that lots of little teams hardly ever get headcount, and starting out as a 20 percenter is the only way to get into one of them.
How are you so convinced you'll hate Google as well? The big plus of working at FAANG is that they have lots of projects and you can switch to something you are interested in. You don't to working on ML in Ads, you can always switch to compilers (dart?), databases (spanner?), VR (daydream?) .. the list goes on. Of course the rat race for promotions, and perf can get disheartening, but you can reach a terminal level (L4) relatively quickly and then focus on what genuinely interests you.