Create some linux instance. Any linux, as long as you can get access to "debootstrap".

Create a separate volume, and attach that volume to your instance (will likely require a reboot).

Once you can see the new volume (something like /dev/xvdb on AWS), run mkfs.ext4 on it, then mount to something like /mnt:

mount /dev/xvdb1 /mnt (your names may vary!)

run debootstrap:

debootstrap --arch amd64 ascii /mnt http://deb.devuan.org/devuan

This will take a while, and you may want to use a local mirror.

After it's done, you might want to chroot in and look around, and maybe add some packages.

mount -o bind /dev /mnt/dev
mount -o bind /sys /mnt/sys
mount -o bind /proc /mnt/proc
chroot /mnt /bin/bash
apt-get update
<install packages normally here, you'll likely need cloud-init>
Add a user, and a base ssh key for that user, so you can log in.
exit

Then, unmount /mnt/dev, /mnt/sys, and /mnt/proc, and finally unmount /mnt.

Take a snapshot of the volume you created. If you (in AWS) then create an instance using this snapshot, and apply the necessary bootloader, it will boot up.

I'm probably missing a few steps here, haven't done this in a little while, but that should get you going. All of this is very AWS-centric, so your steps will likely vary somewhat.

I have hired an instance in development for 3€ per month in scaleway.com

But I only had a choice of debian (there's more OS) buster (need mailman3)

It bothers me a lot to use debian. I've asked them to create a standard image with devuan. I've been told to create it myself. with build image

I suppose "standard" is one image, but I'm not clear on this.

Did someone do this?

It would help to have a reference, I don't get along with virtual ones. 8={ I don't quite understand how an instance in scaleway works. There's a lot of docu but I don't really understand it.

It's an interesting solution that can be easily scaled.

Greetings
Basati