This is good start.

Though it is kind of the technology equivalent of "asking nicely".

I prefer GrapheneOS where my choice is enforced by the OS, rather than passed politely on as a request to the app developer.

At least app developers who ignore it may get kicked off the Apple app store - if they are caught.

For what it's worth, it seems to have been enough to deter Facebook from deploying their latest spyware innovation to iOS.