If the Tiktok app passes your data to Play Services (say, to support notifications with GCM) then it doesn't make any difference that Play Services is nominally "sandboxed".
I agree there's some marginal benefit that sandboxed GApps need to prompt the user for permissions (rather than having privileged system level access) but at the end of the day, Google Maps will get GPS perms and Google will know everywhere your phone goes.
> If the Tiktok app passes your data to Play Services (say, to support notifications with GCM) then it doesn't make any difference that Play Services is nominally "sandboxed".
Sure, but that's the same if you run TikTok with microG (which will relay your data to the Google servers just like the Play Services) or in waydroid on a Mobile Linux. But you can't blame the system for what the apps are allowed to do by the user.
Take your Google Maps example: if the user wants to run Google Maps, obviously they will be sharing data with Google. It's very weird to blame the system for that.
What the sandbox brings is that for users who want to run the Play Services (because they want to run TikTok, knowing that it will share data with some servers, including but not limited to the Google servers through the Play Services), then at least the Play Services are not root on their OS. So then instead of running microG, you can run the Play Services and have the same kind of benefits.
Now if you don't want your apps to contact Google, then by all means, don't install the Play Services! But don't install microG either! And don't install Google Maps!
It's all about trade-offs, it's not an all or nothing situation. Sandboxed Play Services is better than privileged Play Services.