Well technically it does support Dolby Atmos, BT UlSport Ultimate is the only channel with Dolby Atmos, Sky UHD movies only became available in the last year or so and Sky Sports was 'promised' or talked about being available but it's down to Sky, while they keep these options they have the upper hand.
Regarding the Amazon apps you do have prime video, and I believe the Disney + app is only available on Sky due to a deal, but your TV may have the app, as with all apps like this you do need an account, unfortunately none come free unless on a free trial period.