Create layouts as arrays in PHP. You can do this by creating the layout in a field group and exporting it to php. Then copy the array for just the layout that you want to add.
Use the hook acf/validate_field_group. This hook fire no matter where the field group is loaded from (db or json). In your filter, merge the new layout into the field group containing all the other layouts.
This could likely also be done with JSON files if you json encode just the layout array for each layout. You’d need to build your own code to load these layout json files.
