IIRC, Lagoon View rooms are in the Tuvalu and Aotearoa buildings. Hawaii building also has lagoon views, but that is Club Level. Currently, CL isn't a thing, but I don't know if CL will be available when they reopen or not. If not, you might be put in Hawaii as well.
Aotearoa is closer to the main building. Tuvalu is on the water, and will have better views of Seven Seas Lagoon. Hawaii is by the beach and will have views of the MK as well as the Lagoon.
All of these buildings have patios on the first floor and balconies on the third. There are no balconies on the second floor.
For reference, the three DVC buildings (Tokelau, Moorea, and Pago Pago) have balconies on the second and third floors. Of these, only Moorea has rooms with views of the lagoon. It's possible that Disney could put you in a Lake View DVC room. All depends on if they open all buildings on the hotel side, or if the demand is such that it makes more sense to use any available DVC villas.
Steve