This is going to be my next step as well, after switching to Manjaro a couple months ago. Unsurprisingly, after years of using stuff like Google Photos, Play Services, etc , it is not as easy as just a click of a button, but it's definitely worth doing
deGoogle
Yes, using #grapheneos on my Pixel and I'm really happy with that, don't want any other Android OS
Is there an non-google android auto equivalent? Same question for maps?
Android Auto is only from google. For Google Maps you can use OpenStreetMaps
What do you do for google pay? is there any alternative?
I don't use google pay, but hope to see any alternative in future
Are you going Graphene OS?
Yes, people keep suggesting it over lineageOS. That's why I am buying a used Pixel.
I'd like to try Graphene but older Pixel phones are end-of-life or not supported at all. So I again put LineageOS MicroG on my Pixel 3a and 4a. Those phones are super cheap and still great to daily drive. So no Graphene-experience for me, I guess.
LineageOS still uses many Google servers for location, time, etc. in underlying processes.
GrapheneOS have their own servers and are the only ROM to cut those ties to Google.
It's one of those life choices which I also regularly worry about. But the alternatives are almost not available.