Hello
I read your post on lone working. Did you manage to find something suitable?
I was able to use an app called quick time on google play store. It may not be the best as you need to have access to a place they can tap in, however, it is free for the first 50 user Id's you will create.
I hope this helps. I am interested to know if you had managed to overcome this through a different method.
Best Wishes
Claudia
Luna CS