Given that your EOL'd Pebble currently uses servers maintained by an independent nonprofit using an open source stack, it's about as far from Google's influence as anything can be.
My EOL Pebble doesn't use any servers at all, with Gadgetbridge. Why should moving data from my watch to my phone, over bluetooth, require a server on the internet? Silliness.
An app store, watch face store, dictation, weather. those features are the reason it requires a server. That's what you give up by not using rebble or similar services.
You can sideload Pebble apps AFAIR. I vaguely recall doing that recently to restore the watchface on my wife's Pebble after migrating it to a new phone.
