The recent Open Core Patcher commit bbc8902 adds non-Metal support for macOS Sonoma 14.4 on unsupported Mac.
This commit is not yet available as the official release but you can use the nightly build and test it on your Mac.
It’s recommended to update the EFI using the latest OpenCore Patcher (1.4.2) before updating to macOS Sonoma 14.4
It’s also a good idea to have a backup of you data before updating your unsupported Mac with a non-Metal GPU to macOS Sonoma 14.4