Ah, they announced it early this year. Nice.
In the meantime, I ported the current patchset forward to 6.6.66:
https://mc.pp.se/p550_kernel_patches_6.6.66.tar.xz
Three of the 117 patches were already upstreams on the 6.6 branch. There were two minor conflicts, and one case of a kernel API function being renamed. But no big issues. I haven’t tested to apply the patchset to 6.6.67 or 6.6.68, but there’s a good chance it will still work.
Caveat emptor: I don’t build debs of my kernels (I run Gentoo on the P550), so I don’t know if anything in the debian/ dir needs updating.