I don't know what's going on in this thread. Of course PKI needs some root of trust. That root HAS to be predefined. What do people think all the browsers are doing?
Lineage is signed, sure. It needs to be blessed with that root for it to work on that device.
They're assuming PKI is built on a fixed set of root CAs. That's not the case, as others have pointed out - only for major browsers. Subtle nuance, but their shitty, arrogant tone made me not want to elaborate.