Johnex
12
2.4ghz has better penetration through walls. In 2021 you want to use it too, even in 2030 and beyond 
If you are in a hotel or whatever, you want the 2.4ghz to access the hotel AP, then have 5ghz for your local devices.
But yes, dual channel 5ghz is not possible, only half speed. You would need 2 beryl’s connected together WAN to LAN, and do some routing.
As @gvantass suggested, if you don’t want that, you can connect your device via the LAN ports, then use the 5ghz to connect to the other AP in client mode.