According to the latest (2018) RM Careers publication (available from your AFCO), Direct Entry RM Officer specs have reduced from seven to three. Pilot is no longer one of them.
RM Other Ranks can specialise in the following:
Armoured Support (AS), Armourer (ARM), Assault Engineer (AE), Clerk (C), Combat Intelligence (CI), Driver (D), Drill Instructor (DI), General Duties (GD), Heavy Weapons (Air Defence) (HW(AD), Heavy Weapons (Anti-Tank) (HW(ATK)), Heavy Weapons (Mortars) (HW(MOR)), Landing Craft (LC), Metalsmith (MESM), Mountain Leader (ML), Physical Training Instructor (PTI), Platoon Weapons (Machine Gunner) (PW(MG)), Platoon Weapons (Sniper) (PW(S)), Royal Marines Aircrewman (RMAC), Royal Marines Communications Technician (RMCT), Royal Marines Information Systems (RMIS), Royal Marines Medical Assistant (RMMA), Royal Marines Police (RMP), Signaller (S), Special Forces Communicator (SFC), Stores Accountant (SA), Telecommunications Technician (TT), Vehicle Mechanic (VM).
Many who aspire to become RM Officers don't realise that they'll be Troop Commanders in their first year or two. Thereafter their career path and role differs a fair bit from Other Ranks.