If you already have a DE installed (in your case KDE) you would do something like sudo apt install xfce and then restart (I don’t think you actually have to, but I like to reboot after installing a DE). From there you should see a button on your login manager (SDDM for KDE I think?) That lets you pick the DE for the session. Usually looks like a drop down menu.

Fair enough!

Just curious, what do you use instead of Clonezilla? Not using it for a couple decades is shocking to me since I use it at least every couple of months.

I forgot to include but yes this is a software array done with mdadm. Thanks for the steps! I will give these a go.

Forgot to include it in the OP but it was done with mdadm so it is a software raid.

Yes I forgot to include that this was done with mdadm, so a software array.