On my iMac mid 2007 7,1 20-inch, I installed a 1Tb SSD, the T9500, the max of 6GB of memory and a
OSXWiFi - iMac 2007 iMac 2008 - Handoff Continuity - Broadcom BCM94360CD - 802.11 A/B/G/N/AC Bluetooth 4.0. I installed the Catalina DosDude Patcher (Version 10.15.6) and the system runs incredibly well.
I get the Apple Watch password capability, though I am not yet able to auto unlock with my watch. I have AirDrop, handoff and high speed internet. I can watch Apple TV movies smoothly.
So much works well. The Catalina Patcher wit the above mods runs remarkably well on this old machine - only a little slower than my 2016 MacBook Pro.
The last two things I need to get to work is iMovie and Microsoft Teams. These apps crash. I have yet to find a solution to get these to work. I have tried iMovie 10.1.2 through 10.1.9 and none will install. 10.1.10 on up will install but will crash when I add a project.
Microsoft Teams will install but won't load - period.
By the way, I can run VirtualBox with a virtual machine loaded with Mac OS X Tiger 10.4.10 loaded from the original install disks