Personally, not aware of custom reticles as you describe.
Depending on scopes that interest you, you may find something that is useful, fairly close enough. Likely you know, several manufacturers offer ways to determine how your known drops match their product.....
Then can use something like the Strelok App to get a visual of what a given POI will appear like on the reticle.
Resultng in something like this hypothetical with a milgdot...