It's a sad state of the mobile industry that we cannot have a modern mobile experience without utilizing Google and Apple services. You can run a de-Googled Android phone and use all FOSS applications, but the fact of the matter is this mobile experience will never be as seamless or as smooth as fully playing inside these centralized ecosystems. If you want a less than optimal experience and don't want to feel like you're using a modern mobile OS, then you absolutely can abandon them. There will be trade-offs though. It's up to you to decide if they're worth it or not.