Ah, perhaps I could have repeated some context to be clear.
What happened was that while LineageOS already was in the works by committed enthusiasts on the Fairphone 3, /e/OS was ported to the phone independently by developers of the e foundation, and /e/OS came first, and then LineageOS porting efforts on the Fairphone 3 profited from the work done for /e/OS to get LineageOS official (in their terms) … there’s a short mention here: [ROM][UNOFFICIAL] LineageOS 16.0 for FP3.
So, what I was saying was that either by the LineageOS port succeeding by itself, or by the /e/OS port succeeding and thus being available for reference (since /e/OS is based on LineageOS), official (in their terms) LineageOS should somewhen be available on the Fairphone 4.
Today /e/OS became available for the Fairphone 4.