Fautau is a simple iOS app to bulk import images into your photo library.
Fautau requires iOS 14 and Xcode 12 minimum.
To install Fautau, open the Fautau.xcodeproj file using Xcode and run it on your device.
Move the images you want to import to the "Fautau" folder that will appear on your device after the first launch. You can do so using iTunes on your computer, or using the Files app on your device. Then, all you have to do is open the app and tap the "Bulk import" button to start importing your images. You may need to reload the data.