In the fairly recent past, I've played in a gaming group with a woman who, if not affected by some mild form of dwarfism, was especially small, short-fingered and short-limbed (I never asked or heard anyone ask; she wasn't quite short enough to make it obvious and all of us were polite enough not to pry). I don't recall her having any special difficulties (she was of normal or higher intelligence, in a graduate program), other than perhaps having to ask assistance in moving miniatures on the map and retrieving wandering dice a little more frequently than other players.
In general, the only limitations I can foresee with a little person playing TTRPGs are those directly related to their particular condition -- achrondroplasts, for instance, with their shortened digits, may have trouble handling a large number of dice for games like Shadowrun or Tunnels and Trolls; easily compensated by using a dice cup. Anyone below normal height will have the above mentioned issues of reach (as can people of typical height at a table large enough to accommodate a group of more than about five players), and might need some sort of boosted chair to sit comfortably at a table (they'll likely be used to this, as it would also apply at restaurants, office desks, and so forth). Some kinds of dwarfism may have effects on the voice, which can make it hard to be understood at the table (especially if the group gets loud), and a few have effects on brain development that could make it difficult to play any game that's mostly in the mind or highly strategic (that is, chess as much as RPGS).