Sorry, but this is not going to happen.
Not only would it be a lot of work (we had to rework kernel/initramfs build process in LE10 for kernel 5.4/5.10 which would all need to be backported) but it would also put us in the same boat as RPiOS with kodi 18 - broken HEVC playback.
See these unresolved issues:
Kernel 5.10 - Kodi does not play HEVC videos anymore · Issue #4380 · raspberrypi/linux · GitHub
We released LE10 RC1 last weekend and the final release is around the corner so just use that - like many other RPi4 users already do.
so long,
Hias