I would say it depends on more than hardness. It will also depend on toughness and intended use, and what you will accept in terms of edge damage if it is occasionally used rougher than you intended. For example, chopping with two different steels at the same hardness and same edge geometry, the tougher one may roll if you hit a rock, the more brittle one may chip. You might tolerate the rolling but not the chipping, so the brittle steel will have to get a more obtuse edge when resharpened. Also, some steels with very large carbides will not tolerate an extremely acute edge.
However, I think most steels can handle a 30 degree edge and many can go finer, for most things you would want to do. It seems to me knife manufacturers overbuild their knives to limit warranty claims and negative reviews from the lowest common denominator of knife users. That's sensible, but there is a lot of performance you can unlock if you remove a bit of steel at the edge. Try taking one down to 25 inclusive and see what happens. If you find it's too fragile, but a 30 degree micro bevel on it. If that's too fragile, but a 35 degree micrco bevel on it, and so on.
I doubt there is anything like a published guideline for this, because there are a lot of variables and several of them are determined by the user. Some people want an edge that is nearly impossible to damage, some want the highest performance possible and don't mind if they have to treat it like it was made of glass.
