UBPorts has just released Ubuntu Touch 20.04 OTA-3 based on Ubuntu 20.04 LTS with the latest security updates and beta support for PinePhone, PinePhone
Droidian FAQ says you can use Flatpacks and AFAIK some are designed for mobile, there are lots of VPN apps on Flathub, I think Droidian is a better option for me, however UT seem more mature and faster like you said
No UT apps are separate and only work on UT (but they use qt so they are fairly easy to port to Plasma Mobile and SailfishOS).
There is a VPN client for UT AFAIK, and generally the UT ui is a lot faster on lower end devices than Phosh.
Droidian FAQ says you can use Flatpacks and AFAIK some are designed for mobile, there are lots of VPN apps on Flathub, I think Droidian is a better option for me, however UT seem more mature and faster like you said