A striking paradox in Mahāyāna is that whilst it is avowedly non-dualistic, it seems full of dualisms.
Saying that Saṃsāra is Nirvana appears to oblige one to explain why they seem different. So for Nāgārjuna there is the absolute and the relative, for Baso there is the phenomenal world and the truth underlying it, and for almost everyone there is the contrast of delusion and enlightenment.
Dogen is different. For him, reality can be approached by switching between perspectives, specifically between the perspective of one dharma dynamically functioning and the whole network of dependent origination functioning.
So Genjo ( manifestation) is the first, Todatsu ( liberation) is the second.
But they can switch.
Being is the first, Time is the second.
But they can switch.
The perspectives swap places.
The particular and the universal swop places.
Jumping in and out of each other.