As to the energy balance it’s pretty straightforward math actually, let’s go through it:

The energy required to trap water is zero. It can do it completely passively.

The energy required to release the water is same amount of energy it takes to boil water, sensible + latent heat. Incoming solar energy on a good sunny day is 1kw/m^2. 1kg of water takes 0.1kwh of energy to boil. Given that, theoretically the sun can release 10 liters of water every hour!

There are some other materials which actually reduce the sensible and latent heat required to release the water. There are a number of research papers available, they are usually called “hydrogels” or something of the sort.

Solar irradiance capture of commercially available solar absorbers are super high at 95-99% efficiency. The biggest challenge is with insulating the thermal energy, while also continuing the absorb the incoming sun. There are solar water heaters that are purpose built for this, and can provide all the hot water required for a home. Would be a great benefit to a home energy bill since there is a tremendous amount of free solar energy available. I got super hooked on this youtube channel cuz the guy goes through pretty much all the basic concept for solar energy harvesting. Very entertaining!

Alot of the water access could be better off with a filter, agreed there as well. Not all locations are well suited for air water harvesting. If freshwater is available, of course it would make sense to use what is already there. However this is an alternative technology which can be extremely well suited for some areas, maybe some that don’t even have dirty water to filter. Similar to solar + wind power, there are many cases where it makes sense to use one, but not the other.