What about discovering and installing private app that don't use proprietary big tech service, including sending push notifications?
On android this is very easy, you can just search and install apps from fdroid, where all apps has been manually audited to make sure there is no telemetry and proprietary dependencies, including network service dependency.
Fdroid also build all the apps in their app store to prevent developers from secretly inject backdoors (think xz backdoor, and xcode ghost).
I don't believe the fdroid model works in Apple's walled garden.