You need it to boot in 8.x EmuNAND, but if you are using an 7.x or older EmuNAND and a game not requiring an update to 8.x, then you don't need the flashcart to play real cartidge.
A thing to note:
Playing a real cartridge requiring 6.x+ on emuNAND can ask you to reset the savegame because EmuNAND is not using the same encryption key/method than realNAND 6+
So if you already played that cartridge on a RealNAND, you will have to start again.
Same if you start playing on EmuNAND, then switch to realNAND, the save data will be incompatible.
It's probably not an issue if you seek region Free, as you couldn't play that game on your console before, but it's good to know the issue exists with your other games.