(The Russian's were not but,) the Ekranoplan is hypothetically more efficient than boat or plane.

Not being in the water radically decreases drag versus a boat, massively boosting efficiency.

Compared to a plane, the wing-in-ground / ground effect radically boosts lift, which can be used to greatly increase efficiency. Takeoff is energy intense, but compared to climbing to 40,000 ft it's nothing.

Reducing the need for fixed land infrastructure is another colossal perk.

This article here didn't go into lots of details. But there's a lot of write-ups on DARPA's Liberty Lifter ekranoplan program, and efficiency is a key reason for the effort. As well as versatility. See also Boeing's Pelican ULTRA idea. https://www.twz.com/air/liberty-lifter-ekronoplan-demonstrat...https://hn.algolia.com/?q=liberty+Lifter

Also see Regent craft, for a smaller electric hydro-foil lifted wing-in-ground ekranoplan style vehicle. https://www.regentcraft.com/https://news.ycombinator.com/item?id=36051831

They don't do well in open ocean which is why only saw them in Caspian Sea. My understanding is that they need to fly a certain distance above the waves to keep from hitting them. When the waves are big, this pushes them close to ground effect limit.

My guess is that they would be okay for confined seas like Mediterranean. Or uses where they didn't need to keep to schedule.

it is painted navy grey, not coast guard white.... the size is not truely gargantuan so it is probably just a test article, if the bow opens,then it is general purpose cargo, but ic could also be for very long range marine opps, survalence, keeping things edgy stuff