This app was mentioned in 6 comments, with an average of 1.17 upvotes
You can try an app called "My Watches". I've used it a while ago for backups and it worked great. Not sure how it works these days though. I think I found it from the developer posting on Reddit.
https://play.google.com/store/apps/details?id=com.japplis.watchmakercompanion
I doubt it.
The best thing you can do is to export all watches using something like My Watches Companion, tank the BeautifulWatches folder, and reimport just ones you want. I have many copies of watches as I build, and even with 64GB internal, BW folder does get large. I tend to do the clean out every 6 months or so.
If you have root, you can however manage another workaround by creating a bind mount a folder onto the SD card to the internal.
Watchmaker is $5.99 and there's no PC interface. I never bothered to learn how to use it to make my own faces because there are some really talented folks already offering awesome ones. Optional but suggested is My Watches Companion for $1.49 that helps you manage a large collection.
Do you still have the Android phone? If so, you might look to see if there is an iOS version of My Watch Companion: https://play.google.com/store/apps/details?id=com.japplis.watchmakercompanion
That app on Android lets you backup and restore large numbers of watches at a time. In theory, if an iOS version of the app exists, you might be able to backup from Android and then restore the files in iOS.
That would be the only way that I know of to do it in bulk.
Also My Watches Companion is a great tool for managing large collections like this.