I tried looking into this too but couldn't get further than some reddit bickering and a handful of forum posts. Not a Tesla owner myself but might want to be if the privacy issues can be fixed.

Ideally I'd like to keep my cake and eat it: keep navigation (preferably offline), spotify, etc. working but disable the telemetry, remote control, etc. From what I could gather, Teslas can use Wifi (your phone's hotspot) as a backup uplink. So depending on how they've implemented the cloud features, after disconnecting the antennae, you might be able to set up a tiny router and whitelist certain DNS queries, HTTPs connections, etc. But it might also be that they just use a big ol' VPN tunnel to the mothership and pipe all the cloud features through it.

Slightly less ambitious: does the navigation in Teslas work offline? Offline maps and route calculation have been around since the 00's in standalone GPS navigators, so it's not impossible.