I've done some research about this, but most of the posts were for free games and the information for paid games were very vague. I have consent of legal guardian.

Is there a question in there?

Anyway. Research the terms of service.

https://itch.io/docs/legal/terms#2-users-and-publishers

You affirmed that you are 13 years or older by having an Itch acocunt, and if you publish you affirm that you are either more than 18 years of age, or possess legal parental or guardian consent, and are fully able and competent to enter into the terms, conditions, obligations, affirmations, representations and warranties set forth in this Agreement.

You need parental consent, even if you publish free things. You need to pay taxes for what you sell and do a tax interview. Can you do that in your legal situation, do you have the necessary financial accounts to handle the payments and so on.

All these things are usually not worth to bother with for pocket money. And if your projected sales volume is big, just open a small business with your legal guardian as a co-signer or whatever it is called and however this would be legally handled where you are. The thing is, your signature is worth nothing on a contract, if you are a minor. I exaggarate, but this is what it boils down to. "fully able and competent to enter into" ... contracts. You can't do that as a minor on your own for most contracts.

To enter on the customer side of a contract for minors is easier, but you want to enter a contract on the seller's side.