What if you used the Sentinel data (in assuming your using the same low res stuff I view in CalTopo) and put that through an AI up scaling type algo and also give it the higher resolution but older imagery ? With a decent amount of dinklsr data it might be able to fairly accurately give you an approximation of what the current high res stuff is.

I suppose you could even train it (maybe) on multiple years / time periods of historical high and low res data before using the latest Sentinel stuff ?

Edit: I'm sure you already know this but I bet for the above the false color IR data could also be especially useful