I am able to choose both Riviera and Grand Floridian Magic bands. Stay is 7/26 at Pop. I do not think that means they will move me to Grand Floridian. I think it just means anyone can upgrade their magic band to a given number of bands.
That is correct. Long before WDW was ever shut down, they would put resort-specific MB's in the upgraded inventory for anyone to select (the RIV one was available quite a bit last year and early this year). It didn't matter where you were staying - you could still purchase a resort-specific MB in the inventory regardless of where you are staying. Resort-specific MBs being available now give zero indication of what resort you are staying in or where you will be moved (if they move you).