Well I bought the new Laptop and I won't put up with all that Windows 11 crap so it was time to downgrade. For those who are just reading out of interest this is going to be long and fairly technical. So feel free to ignore. If you are interested in this, please continue.
Now this is neither an offered solution nor a recommended solution. The laptop has never been offered in W10 variant so I'm on my own skill and knowledge for this but thought I'd share.
I bought 64gb of RAM from Amazon, £200 instead of the £400 Dell wanted. So first thing I had to do was take the bottom off the device and replace the RAM.
I also didn't know what would happen with the licensing so I bought a £35 Windows 10 Pro license and DVD from ebay.
Since I'm in the land of no support for this my next act was to back up the hard dive. Actually to make a clone image of the drive. This can be kind of temperamental so I have a set of tools I use. Acronis Trueimage 2010 seems to have been corrupted on my machine so I wound up with a demo of Macrium Reflect. I had a good experience cloning my work Dell and actually getting the clone to boot so it was a good choice.
To do this I took out the NVME SSD from inside the machine (bottom already off). First surprise. The 1TB drives are now so small that it needs an adaptor to fit on the board.
I put the drive into a USB NVME caddy and plugged it into my main machine.
Then I created a virtual drive with windows disk management and initialised it.
Macrium reflect saw the two drives and cloned it to the virtual drive for me. A quick check to see I had a clone of the drive and I removed the drive from the caddy and put it back in the machine, put the bottom back on and screwed it all up. This is so much easier than when we had to use a spare hard drive and literally make a physical backup. The cloned drive is a 100GB file on my 20tb external drive.
First challenge. I HATE this sign up for Microsoft BS that they keep pushing on you. Especially as I bought the laptop with Pro and that should have the option to bypass the Microsoft account. Of course it doesn't any more. So I found an article on bypassing that. Before this I'd just capitulated, let them create the account then created my own and removed it later. But why even give them that much satisfaction. Here is an article on how to get around that. I've saved it in OneNote as I don't trust the internet not to lose it.
Next challenge. Experience shows that drivers are the hardest challenge and that it is prudent to back up the drivers from the existing environment (more about that later), before doing anything irreversible.
So I used the Export-WindowsDriver powershell command to extract a directory of drivers for the machine. Windows 11 uses the same driver infrastructure as Windows 10 but some manufacturer packages validate the windows version and refuse to run. So a useful thing to do and can save Extraordinary amounts of time.
There is also a DISM command to export all the drivers in the image. I didn't do that as I was mainly after the explicit additional drivers not added to the image.
Next step is the Windows 10 image. I used Microsoft's Windows 10 Update assistant to build a USB key for installing Windows .
OK so till this point nothing critical broken. Windows 11 is installed and activated. This is an important point I didn't mention. Because once I completed the install it registered the hardware of the machine in the Microsoft database and recognises it for future reinstalls. You don't need a key. Just as well cause you don't get one.
So I booted from the usb key, I updated the bios to boot for it because I couldn't be bothered to go find the keystroke for the boot menu although as it turned out I should have.
It booted from the usb key, went into setup and would not recognise the SSD. I pointed it at the drivers (yes I'd added the drivers to a directory on the USB key which was a bit of an issue as they were 55GB). It told me there were no drivers for the hardware.
This took quite a bit of faffing until, inside the bios, I noted that Dell had enabled the RAID function on the SATA controller. Now I'm not going to go into a rant about what the hell Dell are doing enabling RAID on a controller which only has one drive outlet, that should be obvious.... Anyway I switched it back to SATA and the installer saw the drive.
I removed all partitions on the hard drive and installed W10.
All went well, reboot, back to the setup. Used the OOBE hack again to avoid entering a Microsoft account and then was in and logged in.
I went to the drivers and as I expected I had a list of about 20 drivers not added. So I dutifully went through these drivers adding them from the USB key. This is important as the Inspiron doesn't have a LAN socket on it and the wifi doesn't have a driver in W10. So you can't connect to the internet.
All but one driver installed.
I then was able to get onto the internet and onto the dell site. Dell has done a credible job of upping their game, I installed their support tool and did a driver update. It recognised the machine and offered about 5 more drivers, including the Nvidia graphics driver. It even updated the bios and rebooted into BIOS update mode automatically.
Once that was complete I still had only one driver missing but the whole system was pretty well set up. I checked the registration and it is registered. So I have a spare W10 license.
After going backwards and forwards with the Dell site (the drivers is not intuitive and it tries to force you into only using their update tool), I found the lacking driver, the fingerprint sensor driver and installed it. The dell package doesn't check the OS version between 10 and 11.
At this point I've got a brand new Windows 10 Dell laptop. I installed Kaspersky (having removed the truly dreadful McAfee business machine killer), Installed Office365 and will spend the next 3 months installing back the about 200 apps I generally use on my laptop.
As a side note, just on feel, it is about twice as fast as the Dell software, McAfee nightmare, windows bloatware, installed original image. Something to keep in mind.
Another thing to keep in mind is that I will have a brand new Dell laptop which is basically out of Microsoft support. For some this may be an issue. For me it will be a relief to no longer have my machine rebooting at weird times when Microsoft decided they were going to force feed my machine updates.