I ordered the Sumitomo plug from Eastern Beaver and gave up on finding the other one. I'm not going to remove the fuel tank to look for it.
Ultimately, instead of ordering the plug from Eastern Beaver pictured in my first pic, I could have cut it off and soldered in its place an SAE plug and did the same to the heated grips harness, but I decided to use what's on the bike already.
Glad it worked out. I don’t know of any other accessory/heater grip plug. I think this is the one for the 2017/2018 650s. I bought a ten-pack of the Sumitomos, both male and female. They are easy to work with. I have since hooked up a Garmin Zumo and an accessory lights relay trigger cable in addition to the heated grips, all using these connectors.