I mean, I am not sure if that's interesting for you, but there are alternatives for that as well.

Sharing photos and documents (and many more things that Google's software stack can do) between all those devices is easy with NextCloud/OwnCloud. You can use an independent NC/OC provider, who will let you use this software on their own servers, or you can set it up on your own server for maximum privacy. Obvious difference between Google-provided solutions and independent providers, is that you gain a little more privacy but you have to pay a small fee for costs of operation.

I never needed to use favourite map locations sync, so I can't give you first-hand information. I have a maps plugin on my NextCloud, it allows to set favourite locations, and there is an app that allows to see them on mobile. It's not tightly integrated (it seems to be a list of favourite locations, and it launches external software like OSMAnd to show them on a map) but from the description, seems good enough.

In general, I understand that it's all not for everyone, but the only reason Google's stuff is so universally used, is people's tendency to avoid anything that needs to be paid for, marketing and the fact that the alternatives are largely unknown. (Changing that, hopefully, is the main reason this post exists)

microG allows to have best of both worlds, I am not sure how good for privacy their implementation is, but at least it allows to download apps from Google Play without logging in.