If I go to the topic, click/tap the looking glass icon at the top of the page, enter “uart” and enable searching only in the topic … I get about 30 posts to look at.
Perhaps you could simply send messages to some people who were involved starting from here … https://forum.fairphone.com/t/fp3-custom-rom-development-based-on-released-source-code/56355/172?u=anotherelk.
(Click/tap on the username or avatar - Message)