Hi Dan,
I did extensive testing with this device last year trying to get it to work with Collector. During 3 days of testing, I only managed to get it to successfully connect to Collector once. However, VRS was not enabled so the accuracy wasn't great. It rarely wanted to connect and it took tons of finicking to even get it to connect in the first place.
I used a third-party program called PuTTY to verify that it was sending NMEA signals. I think the main problem is this device wasn't designed for a Collector workflow. It was designed to work specifically with the Topcon software. Although it is a bluetooth GNSS receiver, it's intended use wasn't to pair with mobile devices in the way you're expecting. I tested it on the Windows tablet from Topcon, a Surface Pro, a iPad 4.0, an iPhone 7s, a Samsung Galaxy Tab, and a Google Pixel 3. The only device it worked with was the Topcon Windows tablet and when I say worked, it was that single instance.
If there is a way to get it to work with the workflow you want, I couldn't figure it out. It isn't an Esri-supported device and there is barely any reference out there because of that. Topcon also has subpar resources that weren't helpful. I told our departments using it they would have to contact the vendor for more help because I couldn't provide them anymore. My recommendation is to follow Esri's recommended devices here: Prepare for high-accuracy data collection—Collector for ArcGIS | Documentation. I recommend using iOS devices and one of those receivers because they will be the most heavily tested. Androids "open" nature makes it a little more of a wildcard and from my experience the recommended devices have always worked better on iOS devices.
