Update reaching us says that Opera browser for Android version 51 will soon feature free VPN. This latest announcement from Opera was sent via email to AndroidAuthority and states that the free VPN will be encrypted in the new browser version.
This new update does not require any sign-in to make use of it because it is a browser built-in VPN with a 256-bit connection. Just enable the VPN in-browser, choose a location, and you can browse anonymously.
According to Opera, the rollout had already started but are available on Google Play in a few regions. You can check if the new feature is available in your location by downloading the Opera browser for Android from this Google Play store link.