Thanks for that advice, especially step 1. I investigated and found that there is a Beta version of it which does work with Android, so I'm trying that out.
I'm trying to use Nearby Sharing for the first time with my Android phone. Although I'm signed into my Windows account as an administrator, the Nearby Sharing page demands that I sign into an old work account that I've not had access to in years. How do I change that to be my Windows account...