Surely the intended end-game is to be bought by Shopify with companies like that (or the equivalent of Shopify in their case)?
I don't think this is quite the same personally, since it seems to me more like Gumroad is just what OP picked initially for MVP, and could 'easily' (and with probably exponential value-add?) support more platforms later.
That's a fair question, and that's why I didn't build out everything I had in mind (trends, AI based suggestions, etc), I just put together the best MVP I could in a week and put it out there.
I have discovered other ideas like this but the lack of leverage makes it really hard to justify the squeeze