This is less a tutorial and more of a "yes, it can be done" scenario.   I've been running Devuan on OpenVZ 7 for a few years, with various hosting providers (who obviously don't support Devuan natively).   It's somewhat easy to take a bare metal system, install OpenVZ on it, then install a Devuan guest.

  You will require 2 servers, one can be a home server in a DMZ (has to be web accessible), and the other is the target server at a host provider (say Hetzner).

  On your local server, you will be installing CentOs 7 and Cobbler.  Now, Cobbler itself, doesn't support OpenVZ, so you will need to lightly patch it using this PR: https://github.com/cobbler/cobbler/pull … 0c2287d7aa

  On your target server, you will use the host providers deployment system to install CentOs 7.  Right after installing it, you will install Koan, using the cobbler settings of your server.  For example: 
koan --replace-self --static-interface=eth0 --server=<your home servers' ip> --system=<openvz-system name from cobbler> --no-copy-default

Before you reboot, edit the grub settings and make sure to add 'biosdevname=0' to the kernel line, otherwise you'll get random network adapter names.   You don't need to, but then you'll need to do a some experimenting to see what the names are.  It's also possible to bond interfaces via cobbler.

Then reboot.   If all goes well, the new system will be up and running OpenVZ 7.   Once you have that, you can follow my instructions here for getting Devuan into OpenVZ:
https://github.com/azilber/openvz7-devuan

Cobbler setup is going to be your lengthiest venture, as you'll need to duplicate the provided configs exactly.   It's also possible to use HashiCorp Packer, but I haven't had a chance to mess with it all that much, but it's supported by default for more hosting providers (like Packet.net).