As of right now, haven't tried Sonoma with Haswell. It's probable with a dedicated AMD GPU that still has support. So Polaris or newer. There's a whole thead on AMD graphic support in Graphics forum.
I tried it yesterday. It works With RX6600XT, OC 0.9.3, latest kexts, SMBIOS iMac19,1.
First updated the SMBIOS from iMac18,3 to iMac19,1 (also updated SMBIOS in USBports kext)
Now I can access Sonoma beta in system update. I didn't wanted to risk existing Ventura, so tried to download full installer from Apple. But it was downloading a .ipsw file. Didn't wanted to deal with it. so, downloaded DMG installer from
https://mrmacintosh.com/macos-sonoma-full-installer-database-download-directly-from-apple/
Created a Sonoma APFS volume on the Ventura boot disk, which is NVMe M.2.
Tried to install from the created USB installer, but it failed at installer stage. Then, I directly launched the downloaded installer from Applications folder and installed from it, and it worked smoothly !
Same EFI works with both Ventura and Sonoma. Only change in config is MaxKernel limit of 22.9.9 (Ventura) for NVMeFix.kext (and AirportBrcm, if you have a working wifi in Ventura). Initially added -lilubetaall in boot args, but removed it, as it is not needed with latest kexts.
It doesn't feel like a beta. Stable, and even sleep works well. I don't have Wifi BT card, but they seem to have issues for now.
Sonoma doesn't have many new features, but it feels better than Ventura, and more iOS like. But I hated the screen saver / wallpaper. Can't believe Apple uses such colors. Changed it immediately.