Does joystick position control bank angle in some Airbus aircraft? And what happens when the pilot deflects the joystick when wheels are on ground?
Does joystick position control bank angle rather than directly controlling aileron/spoileron deflection in some Airbus aircraft?


To complement @Bianfable's answer, in Normal Law Flight Mode, Airbus FBW families (including A220) command roll rate via lateral stick position up to the artificial spiral stability limit of 33 deg bank (for A220 it's 30 deg). Below 33 deg bank, the aircraft exhibits neutral spiral stability; beyond 33 deg bank, it exhibits positive spiral stability, and lateral stick position commands a steady-state bank angle up to the roll limit of 66 deg (for A220 it's 80 deg). 


  Also, what happens when the pilot deflects the joystick when the all wheels are on the ground and the bank angle (or roll rate) cannot change substantially?


Upon landing, the Normal Law transitions to Ground Mode, whereby the stick inputs command direct control surface movements. For A320, the lateral control transitions from Flight Mode to Ground Mode in 0.5 sec on ground detection is met, as shown below:




  Also, if the pilot is landing and the left main undercarriage assemblies are not extended for some reason, when the wheels on the right main undercarriage assemblies touch the ground, will maintaining a strong right control input on the joystick help delay the left wingtip (or engine nacelle) from contacting the runway, or not?


From this German accident report, in the case of an asymmetric gear deployment, ground signal is generated if "both LGCIUs (Landing Gear Control Interface Unit) detect that one landing gear has been lowered and is under load, and the radio altimeter measures the height above ground as less than 50 ft".

Therefore, immediately upon touchdown, you can expect the FBW to partially resist roll motion; but after 0.5 sec, you will have to use lateral stick to hold the aircraft level until the airspeed is too low to do so.