Upgrade kernel
Updated kernel to v6.7-rc and updated the mt8183 and x86 configs using make oldconfig. I confirmed the x86 config was able to boot both into a shell and into Ultramarine Linux. I need someone to confirm the new mt8183 config works.
Staying with LTS for bootloader is desirable in my opinion, as it won't require as much maintenance and we don't need new features from upstream.
Not like x86 was on a LTS release at all.
I agree, an LTS kernel makes more sense. I've replaced the one kernel submodule with two (one mainline and one LTS) and modified the Makefile to use the LTS kernel for x86 and the mainline kernel for arm. Also put the v6.6.3 x86 config (from main) back and retested it (it worked). I believe the arm config still needs to be updated.