How can you create a full backup of all photos on a Mac

I have a 4TB MacBook Pro (2021 M1 Pro). The only reason I bought one with so much storage is so that I can download all the original photos in the Photos app and then run backup software (BackBlaze and SuperDuper). That way, if my Mac were to be destroyed, I would have a full backup that does not rely on iCloud.

But what if you don't have enough storage on your Mac, and you have to select "Optimize Mac Storage" in Photos settings? In that scenario, is there some way to still backup all the full-res versions of all your photos? Maybe from iCloud somehow? I know they should all be in iCloud if you have iCloud Photos enabled, but that's not what I'm talking about. I want to get them out of iCloud and on an external drive or a NAS.