How do I sync Voice Memos between my iPhone & my iMac?

Actually, my issue resolved itself: I stepped away to have lunch and when I got back to my computer, I saw all the Voice Memo files from the phone were downloading onto my Mac, so somehow something I had done already had set that in motion.

After perusing your reply and going to my iPhone Voice Memo app I realize what you're showing me is that when you have an individual Voice Memo recording open, you can tap the ellipsis to Save To Files or to Airdrop. I don't know if I had ever noticed the ellipsis there, so that's helpful.

But I had assumed that everything I created on the iPhone in general got saved to the cloud, and in particular that—much like an email in Mail—Voice Memos created on the iPhone would automatically combine chronologically with Voice Memos created on the iMac, so that when you opened the app on either device you would have all your recordings in one place, and I'm still puzzled about why that hadn't happened previously and what took so long for it to happen this morning (or indeed which of the many things I tried was the thing that finally did it—perhaps simply leaving the phone plugged into the computer for the extra hour beyond when it had backed up), but I thank you for your reply.