Brand names in ACNH?

Does anyone know whether it is allowed to create tshirts etc. With brand names on it or whether Nintendo prohibits this?

Is generally not allowed, exceptions are only if you own the rights or have received an order from the brand

I doubt Nintendo or something will sue you then. Just do it as if it really itches someone.

(I don't take any liability! XD)

I think as long as you don't put it up on the internet, everything is fine

Most illegal. You will be shown by the brand if you do something like that