you could give the custom kernel in DRM issue on samsung galaxy S8 (#1766) · Issues · e / Backlog · GitLab a try.
Instead of installing the kernel, just booting it alike to a netboot via fastboot boot boot.img - not sure if this is possible on a locked device, probably not, but would give confirmation.
Then asking Alexandre if he can document what is special about the kernel build and then go upstream to include the mod if there are no disadvantages