I'd be interested in trying an update on Monterey too. Unfortunately, I'm not very good at it. Can you please post your EFI folder?
Try making these changes. Uncheck the three SMD kexts as those are for laptops and dell computers. Also you should have DisableIOMapper checked. I think that is causing your ethernet issue.If your configuration is different than mine it may not work, but hopefully it gets you a head start.
Remember to update your SMBIOS so your iMessage and that stuff works. You can google how to do that.
Also keep in mind, Ethernet is busted. If you find a fix for it let us know!
PS: Best to boot this from a USB and put the final working version on your main SSD/HDD EFI