Is it possible to import photos with their metadata that were exported from google photos with the Google Takeout? There is an accompanying json file for each picture that includes metadata.
digiKam can import metadata from xmp sidecar files. First define what metadata in the json files should be mapped to what xmp field. Don’t map what already exists in exif.
Various tools can create the xml xmp files, but it might involve some scripting. bash + jq + exiftool would be my choice.
A sample json file would be helpful.