Importing photos from Windows PC to Photos
To import photos from multiple/nested folders, open the Mac Photos app > in the top menu, click File > Import. Navigate to where your folders are, and select the top level folder which houses your complete folder hierarchy. Click "Review for Import", then check mark the "Keep Folder Organization" box. This will create an album for each folder. For nested folders, it will preserve the folders / albums hierarchy. Metadata will be preserved, so photos will appear in chronological order based on EXIF dates.