All Linux kernel livepatch stuff are paid services, as I understand it, the Linux kernel live patches aren't possible to just produce automatically, it requires a team with enough Linux kernel knowledge to make it work and usually such teams want to get paid.
Also, I think that the base Linux kpatch tools are open source, but the infrastructure that RedHat/SUSE/Canonical/etc use to provide them are not. However, I think the Gentoo folks do have some open infra code.
> KernelCare understands that hobbyists need protection too, so we offer this benefit to Raspberry Pi enthusiasts free of cost. The currently supported chips are the BCM2711 (Pi 4) and BCM2837 (Pi 3 and later models of the Pi 2), and we offer support for Ubuntu Focal Fossa for 64-bit ARM platform, and soon support for Debian and Raspbian.
https://tuxcare.com/patch-raspberry-pi-systems-without-a-reb...
Also I think you can use Ubuntu PRO on the pi, which includes Livepatch.