When you VPN using your smartphone as a hotspot, can the VPN tell your location like it can when you VPN over a wireless connection hotspot?
I think the answer to that is 'it depends' - I was looking at something similar recently, for example the IPs issued to the AT&T phones we tested all resolved to an Atlanta, GA address - even though none of the devices were within a few hundred miles of Atlanta.
Different carriers are likely to yield different results though - some may yield more accurate results than others.
Trying to tie an IP to a physical location is often unreliable, it depends on the service provider to provide more detailed information about smaller IP blocks than they typically do. It's that much more management overhead.
I never assume that the location mapped to an IP address is correct.