I think seba_dos1 refers to PureOS [0] (for the Librem 5; PureOS is essentially a FSF-endorsed Debian) and Mobian [1]. Both use a close-to-mainline kernel, Mobian's goal is to "bring Debian to mobile devices. Over time, the idea is to minimize the Mobian specific pieces by “upstreaming” customization to the original projects."

[0]: https://pureos.net/

[1]: https://wiki.debian.org/Mobian/