Mobian
The Mobian project aims to bring Debian on mobile devices. It is maintained by 2 distinct (but overlapping) teams:
the Mobian team is responsible for maintaining downstream packages (containing non-upstreamable patches and/or not ready for inclusion into Debian) and non-packaging tasks, such as image generation and distribution
the DebianOnMobile team maintains packages which are already part of the Debian archive.
Also see Mobian on pine64 wiki
Project wiki: https://wiki.mobian.org/
IRC: #mobian on OFTC
Matrix.org: #mobian:matrix.org
Telegram: https://t.me/mobian_project
Salsa: https://salsa.debian.org/Mobian-team/
Gitlab (deprecated as of 2022-07-08): https://gitlab.com/mobian1
For installation instructions see e.g.InstallingDebianOn/PINE64/PinePhone or the community wiki above