If you are willing to get a BQ Ubuntu edition
you can install a VPN on it with a few tweaks to IPtables
or ufw to keep it running properly.
This assumes of course that the particular version of VPN works in China, as some have failed.

Have no illusions about just opening the box
and being able to hack away with it though.
Ubuntu Touch is a linux system that has been castrated and amputated at the knees
by the Ubuntu devs so that it can not run much more than cotton-candy consumer crap.
There is absolutely zip-nada-ada-anything for developers or hackers.
The complete absence of any version of VPN in the corporate store tells the whole story about
who Ubuntu guys sleep with.

I use vpn (no I will not broadcast which one here).

It simply involved generating an .ovpn file and saving it in the right location and a few minor iptable edits.

The Ubuntu operating system is a hopeless trainwreck,
but at least it is not a babbling tout like Android
or a locked prison like Apple.
Because it still can run terminal and mc and has a relatively hackable directory structure it can be tamed to a small degree.

The worst thing about Ubuntu Touch is the utter absence of a sensible email client,
and all the restrictions the devs have locked away from the user adjustment.
If you can stomach all that and just use webmail for your email services (Gmail has an app but I bet it fails in China)
then you might be able to endure.
Because the Ubuntu Devs are so heavy-handed with crippling user rights
there will be little more than the current swarm of
web-fart displays and the bandwidth-guzzling Scopes thingies.
(they re-download things like thumbnails and stuff each-and-every-time you restart a scope - this is fscking insanity)

But at least a VPN can be made to work on it.
My remaining n900 is too fragile to be put through such paces but apt-get install is mostly there and can be accessed if you are sufficiently motivated.