How to sync a folder of images to the iPhone while iCloud Photos is on?

I used My Photo Stream to sync recently taken photos to Photos on my devices. But in moving to iCloud Photos, I discovered another change: once you turn it on, it disables the ability to use iTunes – excuse me, the Finder – to sync a folder outside of the Photos database between an iPhone and the Mac. Apple’s support site just says that this isn’t available if you have iCloud Photos on, but it never explains how else to do it.

As a work-around, I found that I can use iMazing to import the photos from the Mac folder to the iPhone, and it creates the same “From My Mac” album that turning on iCloud Photos rudely deleted.

Is there a better way to do this?

The folder I’m synching contains photos that only need to be on the iPhone and nowhere else. Except of course the Mac, so that they get backed up by my myriad backups strategies.