They tried to use the air to form a skirt to contain the air, but it can’t hold pressure all it can do is slow the escaping air a bit. In effect it can help improve the “ground effect”. But it can’t hold pressure and thus you still need to move a ton of air to keep you hovering, the y tried this on various experiment iirc. I think it was one of the Avro Car experiments perhaps?
The idea for something like steel is interesting but steal does not flex well and is heavy. If you want yo read about something like that go find the Book Hammers Slammers it is a sci fi book written by a Vietnam vet and is about a military mercenary group that uses mostly hover craft.
Having played a bit with Metal armor, chain mail and scale mail and such and that is not going to help a lot. Even when metal armor is maid from aluminum it weighs a lot still. And scale mail is sort of metal plates attached to a backer and overlapping. So they will get ripped off.
As far as I know while the ware and tair on the skirts is an issue and a costly one at that. I think if you look into thinks a lot of the issues with using them inland is that
A) the ground is not smooth and thus the skirt will not seal to the ground as well and will leak air. Depending on how much leaks out it may cost more fuel to run the fan at a higher rate or it may ground the hovercraft, neither are good,
B) hovercrafts maneuver like a fully loaded semi on sheet ice that has been oiled and the semi truck has slick tires. In short the such at turning or stopping and that is a BAD combination.
C) Hovercraft are horribly loud this is bad for many reasons not the least is that it lets the enemy hear you from a long way off and it make communication for your men hard.
D) hovercraft are not energy efficient as they burn fuel not just to move but to lift. A truck uses tires so it only needs fuel to move,
E) the hovercraft is more like an aircraft flying low then a tank and weight is it’s single biggest concern, So trying to armor it is not easy and is all but impossible. And the skirt is especially vulnerable as if every hole no matter how small lets more air escape and that is air you must replace. A big enough hole or enough little wholes and you lose pressurization and you then lose lift. And you are stuck.
So while they have some uses and they are cool, the truth is that are just not practical.
BTW, My brother’s boyhood best friend and our neighbor joined the military and drove LCACs.