I figured it out. It's a hack, but it works. I have an Onyx 1620i Firewire Recording Mixer running perfectly with Ventura! AppleFWAudio.kext was removed from Ventura. I took a Mac that still has Monterey, took AppleFWAudio.kext, and modified it slightly so it would install on Ventura. The installation process is the same as installing any third party kernel extension, so you'll have to grant permission in System Settings once prompted. I made an installer package to make this easier for everybody else. I think for this to work, you must disable SIP first. The google drive link below is a download of the installer package I made. I suggest using the free Suspicious Package application developed by Mothers Ruin Software to inspect this installer package, so you know that it does what I'm telling you it does. https://drive.google.com/file/d/1J5k3lndFmebPOnjlIOY7CEvinSV1xfX0/view?usp=share_link