the only reason you cant fly an R22 solo from the left seat is C of G.
i.e. you are exceeding a/c limitations,
you could on any type that does not specifically ban the practice, subject to C of G.
the question is, "why would you want to ?" as you would need to operate radios etc with left hand from left, or switch cyclic to left hand,then do radios etc with right hand
regards
CF