It absorbs water and breaks up. So yeah, I wouldn't use it outside. Painting might help but I doubt you'd get a sufficiently good seal. Likely to need replacing pretty soon.
I built a small storage shed using OSB on the outside. Providing the roof overhang is good, it is well treated and you don't get damp coming up from below, mine lasted 2 years with no visible signs of age/damage before I moved.
Interesting - better durability than I'd have expected. Looks like a decent shed too, nice one.
I'd still argue that for cladding of a structure, you would want the lifetime to be 5-10 years at the very least, and I don't think OSB would be capable of that.
It absorbs water and breaks up. So yeah, I wouldn't use it outside. Painting might help but I doubt you'd get a sufficiently good seal. Likely to need replacing pretty soon.