That's the wrong question. It's not about how it is okay or not. Of course it is "okay". https://itch.io/games/ai-audio
You need context for such a question. Circumstances, and what you mean with "okay".
If you ask AI haters, you will get a context free answer about AI, that boils down to the view: AI usage = evil. And further discussion would always circle back to that view.
Since you did not provide context, I shall answer for two cases.
You have a game with ai generated visual assets. Generating ai audio assets might make the style consistent with what you already have. Prompts do accept language after all.
You have a hand crafted pixel game. Adding ai music is not gonna improve it. You should start with sound effects and expand from there. Is it games that need a music track, or some old style electronic melody or something like that? Try some from here and test like it feels playing your game with that. https://itch.io/game-assets/free/tag-8-bit/tag-music/tag-no-ai . If you think you need actual music, there are places for that too. The drawback is, that there will be several games using the same music.