Not according to what I understand from them, because that would break their security model. From what I understand, you can fork the application if you want and make your own repository, but you cannot use their logo or brand name, so you have to name it a different store entirely. So, like, Izzy could create one if they wanted to, but it would only have whatever repose they decided to put into it. But if I decided to add, say, Monerujo, I could not do so.