Hi,
my wife got given a 2009 iMac, 8 gig of RAM so I used OpenCore Installer and am now running Monterey on it but I seem to be having some issues with Bluetooth, mainly the Magic mouse, and Microsoft Office and some other programs, anyone else done this and what were their results please?
My main Mac at the moment is a 2010 Mac Pro running Big Sur with an RX580. Enabled by OpenCore. Everything is perfect. Really want a new Mac mini with M1 Max to replace… or am I dreaming? 
Haven’t tried Monterey yet as it’s not polished enough in my experience. Once I’m ready I’m sure OC will work.
I just parted out my 2010 Mac Pro and replaced it with a Mac mini. I have found Monterey to be less buggy than Big Sur. Haven’t really had any problems at all with it. On the limited tests I have done I reckon the Mac mini is about 2.5 times faster than the Mac Pro. I was having trouble on the Mac Pro with the NVMe drive sometimes and also my printer and scanner being recognised. No such problems with the Mac mini. And it’s tiny!