you seem to be talking about 2 different things. The theoretical ceiling of a drone vs the max allowable altitude above home point
I've seen a video, of a Mavic 3 Pro IIRC, actually flying over Mt. Everest
the 500M/1640ft is a restriction of...
Her: Now that we are married you can get rid of some of these drones, right?
Him: You are starting to sound a lot like my ex-wife.
Her: You never told me you were married before!
Him: That's because I wasn't.