Determining fields that have been modified in a script

I am pretty versed in the “Modified Time” field type, and its options to watch certain fields, automation triggers set to watch certain fields, and I use filterByFormula with IS_AFTER({Modified}, “2020-12-18 9:00 AM”), etc to return recently modified records in my API applications. So I know how to retrieve whole records with at least one field that has been modified.

But what I can’t figure out is if there is a way, in a scripting app or automation script block, to select only the fields from a record that have been modified since a certain date/time, for example to then PATCH just those fields through to another service…

The only way I can think of to automate this is to literally make a separate automation watching each field separately and patch them one at a time… I don’t want to do this for several reasons. Rather not PUT the whole thing if I don’t have to.

Any ideas? Thanks.