I want to use Litchi for missions, plannings, etc.
Is it possible to use it to create these tasks with the RC2 remote control without connecting my DJI 4 Pro drone?
The RC2 is locked down so that you cannot install any other applications on it such as Litchi.
You cannot use Litchi’s mobile app Litchi Pilot on the RC2, but you can use the Litchi Hub and export the planned flight to KMZ then import it in DJI Fly: How to use Litchi Hub with DJI Fly (for drones with no SDK support)