Thanks to all for the guidance.  Can I contribute my own story, on how I got Devuan running on RPi5?

The following was done on a Pi5 with a M2 compact Hat and a 1TB NVME.

I tried the main "Get Devuan" page, looking for an ARM or RPi5 version to download
https://www.devuan.org/get-devuan

But I got confused by that, sorry. :-(

Thanks to this topic, found the Latest Builds page.
https://arm-files.devuan.org/RaspberryP … %20Builds/

I chose
rpi-devuan-daedalus-6.1.93-armel-ext4-2025-10-16-0434.img
and flashed that image onto a Class 10 32GB SD card
(sticking to reputable brands with good performance)

Plug that in the Pi and it boots nicely to a command line.
Logon with the default user & pswrd of devuan, devuan
Then use menu-config to setup the basics.
But it is just the command line with no GUI.

Next, what desktop to use? I tried KDE.
sudo apt install kde-full

This was a mistake! From the size of the download and the time it took to install (30 mins +), I was thinking this is a *big* package. Sure enough, on the Pi5, its big, fat and slow. You can get a good idea how old the basic package is when you go looking for whatever Internet Browser comes with it. Firefox and Chrome aren't there, what you get is Konqueror. It felt like lurching back in time by at least ten years.

Next, change to XFCE
sudo apt install xfce4
A smaller download, and quicker to install, which is an encouraging sign.

Also needed lightdm, so that I could switch from KDE to XFCE
sudo apt install lightdm

Sure enough, XFCE is much faster than KDE on the Pi, and a pleasure to use. At this point, I had a stable and usable Devuan desktop booting from the SD card. But still had Raspian on the faster NVME.

Next:
How to copy Devuan from the SD to the NVME?
I wasn't feeling confident enough about using command line tools (dd)
So I tried rpi-clone
https://rpi-clone.jeffgeerling.com/

That talks about cloning an SD card to NVME
sudo rpi-clone nvme0n1
But that just did not work for me.
"Device not found" - even though nvme0n1 was visible with lsblk

Plan B?
Boot from Raspian on the NVME
Plug in a spare USB3 HDD
Use Raspian to install another copy of Raspian onto the spare USB3 HDD.
Then boot Raspian from the USB3 HDD.

Now both the Devuan (on the SD) and the NVME are visible without being active devices.
Use the Raspian Image Copier to clone from SD to NVME.
Shutdown, unplug the spare USB3 HDD.
Put a "backup" label on that and put it on the spare parts shelf.

Reboot from NVME, and here we are now, writing in Pi5 Devuan on the NVME.
Thanks!