I got the Ender Extender kit for my Ender 3 V2 and I am pretty impressed so far.
For a size comparison I put the old build plate on the front left corner. It took me about 45 minutes to do the install. I hardly read the instructions. It’s not finished yet. I need to wire the main board back up and get klipper running on a Pi3. I was thinking to use a Pi4 and get a touch screen but I have so many older Pi3s laying around and small monitors I thought I would just use those instead.
I need to find a build plate that will fit. Once you go PEI you don’t want to use glass again. Also I am thinking to go dual Z axis on this. The printer already had a dual Z upgrade. Just have to put it back on.