It’s not that difficult to build your own kernel based on the official debian one: https://kernel-team.pages.debian.net/kernel-handbook/ch-common-tasks.html#s-common-official

Before clicking the link I thought there was a new restic clone/fork out there…

Did the same in python. Ages ago. And again in python half a decade ago. And again in python a few months ago.

Never repeat anything.

They are still developing and selling Sailfish OS. They just stopped making their own hardware.