Hello there.
I unpacked my original boot.img with your tool, switched the "kernel" part with the GKI I built with latest android12-5.10 build environment. I used gki_defconfig. But it doesn't boot. Is there maybe something different with MTK GKI 2.0 platform? What might be the problem here?
Here are my original images and the GKI Image I built.
https://drive.google.com/drive/folders/1VPC6lM7kWc0wTaxTcZFCwBbvRxCnvbQ9?usp=share_link