Just my humble opinion: On a 4,1 flashed to 5,1.
I have Monterey working flawlessly on a 2Tb 2.5" SSD.
I backed this up, to a pair of HDDs in an external USB 3.0 RAID 0 .
I also have two Fusion drives (make them in Catalina via USB flash drive installer c/o Dos Dude) of 2.5 and 3Tb.
I installed Monterey on one Fusion Drive, from a USB flash drive installer c/o OCLP and then after I had done that, I used Migration assistant, to move all the files from the aforementioned Monterey back up, to the new Monterey Fusion Drive.
OK so now I have a working install of my Monterey set up, on a fusion drive.
Then I did the Sonoma, over the air upgrade. I found this once before, get a working Monterey install, then upgrade it OTA for Sonoma.
Success! but it is important to note that I use the 1st Monterey install as my daily driver and the Sonoma Fusion Drive is "experimental" and I expect it to give me conniptions at any time.
Also there are times in this process where the whole, thing looks like it's hung. I just turned the monitor off and went to bed, in the morning there was completion, of what ever process I thought had hung.
More fun than raping a Rhinoceros!