Is it possible to share a VPN connection over WiFi Hotspot?
Yes its possible, I have covered one method to achieve this already on this post.

Alternatively, our fellow user, Mygod has shared one application to achieve this called VPN Hotspot and is available both on XDA Labs or F-Droid. As expected both these methods need root,  for non root solution you may have to look at something like PDANet+