Yes, Vivo S1 does have the Corning Gorilla Glass 5.
Yes, Vivo S1 has an in-display fingerprint scanner.
No. Vivo S1 does not have the 5G network support. It works on 2G/3G & 4G GSM networks.
No. Vivo S1 does not have the front camera flash. It has a display-screen flash.