I'm not sure why this is so difficult to implement. I'm probably missing something. There are 2 options to implement this in my view.
option 1:
Do a 2 pass retrieval: Pass 1 to do a SObject describe for items that had child filters and then Pass 2 to use the describe results to apply the filters (regex or named) and then build a very specific manifest file with exact list of CustomFields. Use the manifest file to retrieve only the fields of interest. The same logic can be used for other child metadata entities such as list views etc.
option 2:
Retrieve everything including the managed fields but then filter the contents post retrieval before the comparison is run. Gearset already does this post-retrieve parsing for things like profiles and permission sets so I don't see why this can't be extended
I'm not sure why this is so difficult to implement. I'm probably missing something. There are 2 options to implement this in my view.
option 1:
Do a 2 pass retrieval: Pass 1 to do a SObject describe for items that had child filters and then Pass 2 to use the describe results to apply the filters (regex or named) and then build a very specific manifest file with exact list of CustomFields. Use the manifest file to retrieve only the fields of interest. The same logic can be used for other child metadata entities such as list views etc.
option 2:
Retrieve everything including the managed fields but then filter the contents post retrieval before the comparison is run. Gearset already does this post-retrieve parsing for things like profiles and permission sets so I don't see why this can't be extended