With the release of 10.3.1. Where does it report true location accuracy with compatible devices? Is a Garmin GLO External GPS unit a compatible device?
I purchased a Garmin Glo early this year and have tried it out with Collector 10.3.2 and it works fine. I'm not sure how to answer your question on displaying accuracy. That may depend on how Collector has been set up. I offer the following on using Garmin Glo with ArcMap. I'm sure there are others better able to answer your questions on Collector.
In the last day I have been able to utilize Garmin Glo with ArcMap 10.3.0.4. I purchased the Garmin Glo at the beginning of the year and wasn't successful in getting it to work with anything on my computer (Windows 7). This was a Bluetooth setup issue on my computer. Yesterday I uninstalled everything dealing with Bluetooth, reinstalled Bluetooth drivers specific for my USB Bluetooth dongle, and Garmin Glo paired up with ArcMap on the first try. If by positional accuracy you mean DOP then the answer would be yes. That is visible in ArcMap by selecting GPS Position from the GPS drop down menu. It also can be recorded in the GPS log (export).