There is some discussion in this thread: https://community.esri.com/thread/180792. There are some links for obtaining this data when using an external device connected to an iOS or Windows version of Collector. I would also like to be able to capture this data using the device's internal GPS.
Yes, you can record information for point features when using the GPS to collect or update the position using your GPS regardless of whether you are using an integrated receiver or an external GNSS receiver. You'll need to add some specific fields to your feature class to allow Collector to store this information (we look for well-known fields). There are a set of python scripts to help you quickly add these to your feature classes. You can read more about this here: Record GPS metadata—Collector for ArcGIS | ArcGIS. Depending on the receiver we may only get a subset of the information about the position (in these cases the OS does not provide all the information to us).
Yes, Collector 10.4 for Android has not yet been released (though expected soon). Once released, the capability will be common across all three platforms (Android, iOS, Windows).
I did some data collection last week at the Esri GeoConX conference in Phoenix, AZ with the Android version and Trimble R1. It worked great. My android phone is a Galaxy S6.
I saw between 40 to 60 CM Horizontal with "SBAS" corrections depending on line of site and the environment I was in (Trees, Buildings and Mountains).
I will be doing some testing on control points in the next week or so with and Trimble R2 Sub Foot and Trimble R2 Centimeter with both Android and iOS latest releases.