I used an iOS app called Gemini 2 (by MacPaw, of CleanMyMac fame) to search for duplicates and blurred or otherwise unwanted photos on my iPhone. As that device is connected to every other Photo(s) app in iOS or macOS via the magic of iCloud, I removed 500 out of almost 8800 photos.
The app uses the subscription model with three levels: 3-day trial; $2.99 per month or $16.99 per annum. I chose the 3-day trial & then deleted the app & cancelled the trial because I am cheap.