The setting to allow unsigned apps could be per appstore tracked by an on-device sqlite database, so a badly-behaving app will be known by its installer.
"We urge regulators to safeguard the ability of alternative app stores and open-source projects to operate freely, and to protect developers who cannot or will not comply with exclusionary registration schemes and demands for personal information."
https://f-droid.org/2025/09/29/google-developer-registration...
edit: because the next step would be Google paying F-Droid a half-billion dollars for default search engine placement, or something else stupid. It becomes a captured organization, an excuse subsidiary.
The secondary device would basically be built on a open platform etc. Once we can't use the phone for sharing the connection, then we are basically stuck using other wireless connections, LoRa for short to medium connections, direct wifi links and offline home cloud environments. It gets a bit grim when you think about it, but there are always options. Now, would you travel with a home made tablet phone in an airport for example? What a about a train station with xray scanners. Cyberpunk always comes to mind as well when thinking of these possible futures.