I asked in the equipment thread but this place seems appropriate too, since you people swim

I want to get one of these underwater masks with an air tank, but I was just wondering what your guys's experiences are with it? how long do you usually last underwater on what volume tank?
I see aliexpress (lol) is also selling smaller scuba kits, just a 2L tank and face mask connected to it, what about those?

everything swimming/water equipment related is a clusterfuck of everyone shilling different things and there is zero sense to be made. I just want to dive closer to the bottom of the sea and see stuff.