Isn’t that the A through F rating system used by bureaucrats worldwide?
I think what you are looking for is a range from eligible for premium subsidy, to regular subsidy, to reduced subsidy, to no subsidy but licensed, to maximum allowed in an unlicensed home daycare.
We have such a structure here in NJ. NJ is not typically worth emulating, but it sounds like what you are looking for.
As far as a specific set of tools or what to look for, I think that good judgement is called for, but a specific list would quickly fall victim to Goodhart’s law (when a metric becomes a target, it ceases to be a good metric)