You can't "move" it yet but there's a trick (involving redownloading the whole game) :
- archive the game in the Switch Storage settings (it will delete the game files from the SD but keep the save on the console)
- turn OFF the Switch (press power for 3 sec then Power Settings, turn off)
- remove the SD card
- turn ON the Switch
- download LEGO
- once downloaded, turn the Switch OFF
- put the SD card back
- turn ON the Switch
- LEGO is still on the Internal Storage and will be played from there.
Note : don"t try to keep LEGO on the SD card before removing the SD, once you put back the SD card it will delete LEGO from internal if already on the SD, it can't be on both storages.
Ha nice one, thanks I'll be doing that for every new game I get until they let us move them across!