Smartphones, mobile apps, mobile networks, and WiFi stopped being your friends around 2015-2016. Now it's just a matter of how much data can be harvested from device sensors in real time until reaching a pain point which doesn't exist.
And the FLOSS/Linux phone hardware attempts have frankly sucked.
I was hoping that my PinePhone Pro would actually be usable. But no, its a PineDoorstop.
Proper Linux would be a great 3rd choice. But yeah. We've got a duopoly and not much we can do about it.