The Alpine Linux Code of Conduct is followed in postmarketOS.
Alpine is the distribution we are based on, and our communities work closely together. The CoC is reasonable, it boils down to using your brain and being nice to each other. It is what we have been living since the project was started, for example people who were rude towards others have been kicked from chats.
It helps to have this written down in detail, and when interacting with Alpine you should be aware of this anyway. So it made sense to adopt this CoC for postmarketOS.