I think technically it's a whole under the table thing, but hussie has gone on record to say that she doesn't really care about monetization iirc? I know plenty of mspfas who had their items monetized (and even kittyquest was selling merch before they were in fraf)and they didn't get into any trouble. It just depends if hicu wants to crack down on these sorts of things or not, and right now it doesn't seem like they will.
Also Im not a lawyer, this isnt legal advice, yada yada yada etc etc etc if you get arrested it's not my fault.