that the only Black piece that can move is the bishop, and there is nothing it can achieve. If White could remove their Bishop that's in the Queen's way on d3, it would almost force the f4 pawn to capture and deliver checkmate, except that with the Bishop gone now the Black King would be able to move. So we need to cover its escape square first.
A nice idea that doesn't work
is to have the knight travel to capture the wandering bishop and make fxQ the only possible move. It is nice to see that the knight can come as close as g3 safely (since capturing it on g3 would be checkmate which Black is trying to avoid), but then the bishop can simply avoid the h1 square and capturing it would allow uncontrollable pawn moves/promotions.
It is a pity that there is no solution where the bishop moves to c4, forcing selfmate but this time with two possible checkmating pieces, the pawn and the newly unpinned bishop on c5. Indeed, for such a solution to exist, you would need to be able to protect the bishop on c4 and cover the escape square c2, which could be done by the knight only if the a3 square was available.
[FEN "7N/8/2R2B2/1pb1n3/1P2Pp1p/B1kBQp1p/2P1pK1P/4R1Nb w - - 0 1"]
1. Nf7 Bg2 2. Nd6 Bf1 3. Nb7 Bg2 4. Na5 Bh1 5. Nb3 Bg2 6. Na1 Bh1 7. Bxb5+ fxe3#
The concept that could be considered arising from this problem could be
Toroidal chess. Identifying the opposite pairs of edges of the board would allow the knight to jump to the desired square in two moves:
1. Nb7 ... 2. Na1