This kind of impersonation/defamation is one of the edge cases where its good to have a DMCA process. You want to quickly take down something like this and then deal with the slow legal stuff over time.
>>johnny+(OP)
They have a DMCA process. As far as I know it only helps in a case like this if they sue Funko or the brand management service. Itch is a small indie operation funded by actual commerce, so might not be able to afford it.