Did some more digging. GPS Menu Pez included an information tool which revealed this is a Mesada device. So I went looking for serial port information for Mesada and found
[Please Register or Login to download file] There's a text file there with the very last line
Navigation interface type: UART-COM2 4800bps
I changed the settings for the port to those and now iGO sees the receiver and gets data (when outdoors). Now, what about increasing the port speed? I got Cregedit 0.0.5.2, which was very difficult to find a site that actually had it without expecting money, signing up, allowing it to spam me with notifications, or only had a link to the dead original download site.