Nice puzzle :)
Struggled with that one :(
Curious if black plays 1...Qf3+ right away. After 2 QxQ e1=Q the knight is pinned. But, 3 Rc8+ Kh7 4 Qb8 should do it.
White could have matted with 5. Qf8 But I suppose the game was timed and the mate here is nice too
Not quite, because white is in check.