I ran into this issue the other day when I leveled a team from 10-50 without touching BFA.

However I didn't need to reach friendly with any faction to get WQ unlocked.

I just needed to completed my heart of azeroth quest, once I completed this I got the United Nations quest or whatever it's called to unlock world quests.

If you don't get the heart of azeroth quest automatically upon getting kicked out of timewalking and put into SW (I didn't get it the first time), then you need to talk to the iron dwarf looking guy that stands next to the turtle that gives you a weekly quest (I'm only familiar with Boralus so this may differ on Horde) and this will start the HoA questline for you.

If you don't see the dwarve AND don't get the quest automatically, you may need to complete the introductory 5 or so quests in your BFA capital city, once you get the achievement from this (Come Sail Away for Alliance) the dwarf should appear and you should be able to start the HoA questline.