I don't think that would be a good idea -- sticking to positive normals and truncating below is enough for float32 and float64. I mean, consider that 1.1754944f-38 is a normal 32 bit float.

The probability that your "perfect" code would ever get triggered is such that humankind has not built enough compute to expect to get that unlucky yet.

(you may ask: why then care about that possibility if it's dead code anyway? Because of security vulns in context of flawed RNGs. Bad underlying RNG leading to bad distributions is expected; bad underlying RNG leading to RCE is not OK. So don't ever output zero or subnormals!)

For bfloat16 the same holds; for ieee float16, well, I have no clue what we want.