I should have mentioned that I do want to have my iPhone/iPad photos backed up to iCloud, just not the ones on my laptop that were taken with a regular camera to save on my phone storage space (I am aware of the Optimize iPhone Storage setting).
Would it work if I kept my Mac photos folder as an iCloud Drive folder instead?
That’s a bit tough, the only way would be to yes, keep the icloud settings turned on to be backed up to the cloud.
So to get this straight you want to back up your Mac and iphone/ipad photos under the same account and not worry about each other‘s pictures downloading to be either the Mac or iphone correct?
Once you upload your photo from your idevice to the cloud it will converge with the Mac, but it won’t download to your Mac and viceversa because you have the optimized iphone storage setting on.
What happens is that you will see a cached version of your picture that won’t download to your device unless you want to see it, until then you can see your Mac pictures but they won’t download unless you specifically ask it to. Then you can do a prolonged hold to delete it from your device if it takes too much space.
By default though iphoto sorts the pictures by dates, or different categories like portrait, selfies, etc but you can manually create your own album similar to a folder and create more sub folders and sort them out that way.
I had this exact problem because I wanted to have a way to see all my pictures from all devices so i had to upload all my photos to my ipad and it synced them up to the cloud, ever since, i just download them manually from icloud.com and back them on another hard drive just in Case because i realized that manually backing them up from an ipad and iphone was always almost impossible.