I've sold some stuff on RedBubble, I don't create much content to be honest, original stuff doesn't sell much, but fanarts do.
However you'll need to check out what are the available brands and corporations that are associated with RB so you don't have your content taken down.
Like, some weeks ago the BNHA stickers I've made were taken down, they were originally allowed for almost 6 years and BNHA was part of the bundle of Netflix's agreement.
I have never bought anything, due to some limitations on my own country, so I won't know what the quality of the product is like, or how well the designs look once printed. But I even had some people commissioning me specific designs, just so they could buy it through RedBubble later. Its a shame I never got the chance to ask these clients for pictures, besides back then I was a bit shy to do so.