Thankful for our friends.
I’m deleting 100,000+ photos on Google Photos by hand. My method is to search for a month (say, March 2019) and then select all (select first photo, shift click last photo) and hit the Trash can. GP was my tertiary cloud backup anyway.
Giving Apple One a try. If I didn’t need Microsoft Office (which comes with a fair bit of One Drive space) I could see buying all Apple storage in the future.