You're correct. The ban targets the supply chain and future imports/sales, not retroactive possession. New foreign drones cannot be certified for sale in the US market going forward. Existing drones you already own aren't being confiscated or made illegal to fly
I thought the drones had geofencing, so it should be possible to geofence the entire US and block them that way?
For now. FCC could change this in a couple of months. There is talk of canceling FCC certifications for Autel/DJI.