I guess you can test the multiplayer aspect using a terminal to open another port, or some procedure of the sort. I’ll give it a try. :)
(By the way, funny seeing you here: I had stumbled upon your comment for Gem Drilla Inc from Mini Jam 109. :) Small world!)
PS: no, in the end, as I am not sure of how the game handles the connection process under the hood, it might be complicated to simulate a connection locally. :/