Does your Garmin have NMEA2K? Mine looked like it did in the manual but it was actually NM0183. Different connector, different protocol.
I had the earlier engine and managed to get hold of a discontinued Lowrance Suzuki interface, you will need the current one (v3.5) as sold by Suzuki and set up a 2K network. Fairly simple.
(If you did go the SMG4 route, one currently on Ebay from Poland, then you don't need a programmable interface at all, just the correct dumb cable.)
Much info as a sticky post on the Suzuki Outboard Forum.
https://www.suzukioutboardforum.com/...a2000-networks