I'm from Volla. We think, that a convenient VPN app for Ubuntu Touch would be a good idea, because the VPN from in the settings is only for experienced users. I think of a simple login in form and a selection of the country.
We are working with Hide.me for the Volla Phone, who provides a simple REST API for the available server and OpenVPN scripts. Further more they will publish soon the source code for a Linux WireGuard command line tool.
Is someone interested to work on this app? We could spend a Volla Phone as a thank you for the effort. Let me know.