When the Cannon was introduced it could be called ground-breaking, because it introduced an entirely new class of moves: obligatory hopping over other pieces. Such moves are not as elementary as leaps, because they depend on occupancy of other squares than the origin and destination of the move. But one could already say that of sliding moves, which require all passed-over squares to be empty; the hoppers just impose another, more general condition than emptiness on such squares. Xiangqi is also somewhat unique in that it confines certain pieces to certain zones of the board; this could be seen as a special case of endowing pieces with location-dependent moves (namely scrapping precisely those moves that would leave the zone, in each location), which is very un-chess-like.

You are correct in pointing out the large Shogi variants are mostly just run-of-the-mill Chess variants, except for perhaps a hand full of innovative pieces (Lion, Hook Mover, Fire Demon.) But they still have a very different and easily recognized 'flavor': pieces tend to move only along the principal (orthogonal or diagonal) rays, and oblique leaps are almost completely absent. (And those that are there are then usually an incidental consequence of some multi-move rule, such as Lion = double-move King.) I have a theory that this is a consequence of the different Pawn move: the FIDE Pawn, capturing diagonally, tends to form chains of Pawns protecting each other. Which are very hard to break down by frontal attack once the chains interlock. You then need oblique leaps badly to be able to undermine these structures by attacking their weak spots in the rear, which are usually unreachable by Queen-moves only. And it doesn't matter much how few pieces you have that can make the move required in the case at hand, as the Pawn chains are quasi-static structures, and won't go away. So you will have enough time to manoeuvre the required piece into position. Shogi has none of this, as Pawns can never protect each other there (and after the invention of drops they added a rule for keeping it that way!). So there is no great need for oblique moves, and to get a large-enough variety of pieces with Queen-moves only, they turned to pieces with very low symmetry.

Another distinctive trait of the Shogi flavor is that virtually all pieces can promote (usually only with modest gain in abilities), while in western variants promotion is reserved for Pawns, offering the possibility to turn the weakest piece into the strongest one. In principle these traits could be easily mixed, but in practice this is not often done. Scirocco is a good example of a chess variant that combines design characteristics of Shogi and western chess variants.

But since the invention of the Cannon and the Grasshopper, and the introduction of asymmetric pieces, putting such moves on a piece in some combination that was never used before can no longer be called 'innovative'. There must be millions of such combinations possible even on an 8x8 board, and I am pretty sure the combination of moving diagonally forward like a Cannon, leaping like a Camel, and moving backwards like a Xiangqi Elephant (just to name something crazy) has never been tried. So what? Unless there is a very good reason why this move would make the game it appears in better than any other, 'inventing' the piece is not more creative than writing down a random number of 60 digits of which you can be virtually certain no one in the Universe has ever used (or even thought of) it before.

Truly innovative pieces are for instance Mats Winther's bifurcators, which generalize the principle of a hopper in various ways (by not only allowing change of move/capture rights on encountering an obstacle in their path, but also of the move direction, and the exact location where this change occurs). Inventors also often resort to associating a move with side effects to create something new, usually locust capture at squares that in various different ways can depend on the move (e.g. Advancers, Withdrawers), but also displacement of pieces on such squares (Magnetic or Catapult pieces).

I do not consider games like Ultima or Aarima chess variants at all. Even Paco Shako is a dubious case. Replacement capture is one of the defining traits of chess variants, and while it is OK to have the occasional exception (such as e.p. capture), a game that does (almost) entirely away with it no longer feels like chess at all. You might as well call Checkers, Ataxx or Amazons a chess variant. Clobber is a somewhat dubious case. 'Chess variant' is not a synonym for 'board game'.