3) there are tons of other apps in which exluded users can have groups an use other features with other multiplatform users.
You can't sue a company because in just their official app it won't support a protocol develop by others. Just install another app, no monopoly here.
you don't need to know the names, just that two bluetooth-enabled devices were in close proximity in a given time window. you'd do all the processing on the device to maximize privacy.
each device would record beacons (which could be fixed, active bluetooth devices rather than just passive beacons) on entry and exit for relevant locations (like grocery stores). you'd tell your device when you got symptoms and give permission to upload the relevant location/time pairs (but no personal id) in the last N days to a research database (not hosted by google, amazon, ibm, and the like).
with user permission, other devices would subscribe to such data for a given region(s), which would be downloaded periodically to the device. the device wouldthen determins if you've had any crossings with known location/time pairs and alert the user.
no need to share extraneous personally identifying info with giant third-parties and potentially with (hidden) state actors. this cuts apple and google out of the data collection game, especially from making it part of the underlying OS, which is particularly dangerous.
