They don’t have to. AltStore and Signulous allow uploading any IPA file to your phone. Apple is not in control there. AltStore PAL is checked by Apple, but AltStore through AltStore server is not. Signulous allows you to upload anything and I’ve used it multiple times for lewd games.
Search em online (I don’t wanna post links here). They are both pretty easy to use and AltStore (don’t use PAL) is free. Signulous is cheap but not free
