Yes, Vivo Y91 does have the VoLTE support.
Yes, Vivo Y91 does have the fingerprint scanner. It also has the face unlock support.
Yes, Vivo Y91 does have the memory card slot. You can use 2 Sim cards and a MicroSD card at the same time.
Yes, you can play PUBG game on Vivo Y91 easily. Please check the following video which will give you more idea about the gaming performance on Vivo Y91.