Well naturally it will need to connect to your phone via Bluetooth for the app to proxy update downloads and historic location data uploads. But in order to do anything on the network securely you need an accurate clock and the ability to parse datetimes because the PKI implementation depends on that.

Then the app pings you to remind you that your premium subscription will be expiring soon after which your heart rate will be limited to 100 bpm or less.

Hopefully no real pacemaker manufacturer is allowed to do that. Creating radiation in the middle of a body near a critical organ without a medical reason sounds like a really dumb idea.

Also you want the pacemaker to be as air-gapped and simple as possible, because it needs 100% uptime.

(maybe I missed the implied /s)