Pretty good for a beginner! It's not yet a formal directmate composition but much better than most puzzles posted here in chess.com style. It is hard to solve mainly because solvers do not know which puzzle standards apply. For instance, solutions to formal compositions never start with a check giving move and the solution length (mate in 4 here) is always provided as part of the challenge. It is actually very hard to solve directmate problems without being given the number of moves. Chess.com puzzles never do because they use more natural (gamelike) positions and are therefore much easier. Also, they do not care about starting checks or about checkmating. Often winning a piece is good enough which places the puzzle in a completely different type if it were a formal composition.
The Novotny device is OK though I have rarely seen it initiated by a checking move. The assumption is that blocking 2 lines is harsh enough to force the opposite side to reopen one. Up to the composer to make that assumption work. However, I don't think there is a rule against a checking Novotny move, and they are probably OK in a presentation with multiple Novotny's in the content.
The first decent puzzle I have ever composed. I will include some other lines in the text after the puzzle is solved.