The website https://airportweather.com/ uses existing real METARs and TAFs and weather models to interpolate the weather conditions at all possible fields that do not have METARs and TAFs, even your favorite local grass field.
Reportedly you already use part of their service for the "flyable conditions" layer.
Could it be possible to integrate calculated field METARs and TAFs in SkyDemon? Maybe a selectable option?
"calculated" METARs must be easily distinguished from "real" METARs.
The site itself keeps the standard METAR format but appends a "RMK SRC AIRPORTWEATHER-COM" comment at the end.
On the SD map you could also use the weather badge (the little circle with V/M/I), maybe having a thick border for real met report and thin or dotted for calculated or something like that?