Hello. The files already have the file extensions, but the game is offered in many formats such as the Analogue Pocket and all are included in a zip file. What you asking is to offer it as a stand-alone file (outside the zip with all the different files)?
Ah yes, I was basing myself on individual files (for example: https://vorvy.itch.io/solastra).
But since I do recognize that many ROMS are also served as zip files, I'm adding support for that as well.
I'll purchase the game to test the zip file use-case, and I'd love to play the game anyway :)