I agree, it must be computer BIOS/UEFI firmware at fault - remind me never to buy one of those!

I've had positive experiences with previous Lenovos. But predecessor rmodels didn't have secure boot nor were they password protected.

I'm just wondering how the Debian USB stick was created. Why did it start no problem.

But I have to move on to complete my set-up.
I'll need a bit more assistance with a few niggles - but they're just due to lack of experience on my side.

@Élisabeth . . . your tenacity is quite extraordinary!  Congratulations!

Thank you! It's often been remarked upon by co-workers, and saved a couple of projects.

I could have had Debian on day one and to be honest it probably wouldn't have made an iota of a difference to my life as the end user that I am now.
But it became a matter of principle
a) not to give up b) to support free software

I agree, it must be computer BIOS/UEFI firmware at fault - remind me never to buy one of those!

Maybe the firmware depends on SystemD    ( For those with no sense of humor it was a joke )

I also suspect the laptop's firmware. I wonder if an update is available. On the other hand we can not ignore that the Debian flash drive did work while the Devuan drive did not. Maybe Debian has worked some magic to get around the issue.  Seems to be a cat and mouse game.

A personal testimony:  I've had nothing but success with Lenovo laptops . . .but then again the first thing I do is change settings in the bios, which OP is unable to do in this situation.  That does make a big difference.

@Élisabeth . . . your tenacity is quite extraordinary!  Congratulations!

+1

Still, I would like to know what the hell is going on the Élisabeth laptop. I've been intrigued since her first messages (but unable to help) and I feel that still nobody of us really knows what is happening. May be a bug in BIOS firmware? I said that just like a curiosity beause life is short and Devuan is already running in Élisabeth computer.

Just noticed, you were putting the image file onto sdb1 - it should be sdb - the disk, not a partition!

creating the output on sdb caused Secure Boot Access Denied error
creating the output on sdb1 caused the boot request to be ignored

I tried all three USB ports.

Anyway, Devuan is running on the PC.

Thanks to everyone who helped me get there!

EDIT: Just noticed, you were putting the image file onto sdb1 - it should be sdb - the disk, not a partition!

I was able to boot from my Devuan USB stick as described in this post - if and if only the Debian USB stick was present in another USB port.

I was able to install Devuan without problems using an EFI partitioning scheme.

As a matter of curiosity, I just created a USB installation drive with  dd under Devuan.

dd if=/home/elisabeth/Downloads/devuan_chimaera_4.0.beta-20210913_amd64_netinstall.iso of=/dev/sdb1 bs=1M 

But just like with all the USB tools I had created on Windows,  my PC couldn't boot from this either.

I guess I'm late to the conversation, but might I suggest using Balena Etcher to write the flash drive. It's a good tool and has a windows version. I suggest it because it worked for me when I had to create a Linux USB drive in windows.  I can't promise it will work, but it can't hurt to try.

Late to the party but I tried out of curiosity:

Chimeara netinstall | Balena Etcher|  Secure Boot Access Denied error

Stupid question: why not proceed with my Debian USB inserted? I can boot Devuan and through the installation menu and make my choices. Do you think my  Devuan USB won't be suitable for the actual installation ?

Not stupid; yes, you should go ahead and try to install that way; whatever the outcome, it'll be an improvement

You will also have the backup path of just installing Debian and when that is up, return to installing Devuan.

I've read this thread and it seems there's been much confusion about this process, but there is a simple solution: use Rufus to create the boot USB stick under Windows.  Rufus has always worked under Windows for me to make bootable Linux sticks for many distros: Debian, Devuan, Linux Mint, Slackware, CentOS, et cetera.  Rufus is "intelligent" when creating USB boot sticks and you do not have to install Rufus if you use its "portable" edition.  It has great support if you need it also.  Best part: it's free.   I hope this helps.

+1 Rufus, had always worked for me too.

I just want to get rid of this Windows shit and recreate what I had before my revious Linux laptop died.

Just found something in a German laptop forum about rufus and Secure Boot: rufus does not write a valid Secure Boot signature. That means in your case rufus isn't the right tool.

That'll be why this is the only burn tool that returns the Secure Boot error with netinstall.

I'm impressed - you're multi-lingual.