Multiple Photos (&iPhoto) libraries, Macs, iPhones, etc

Over the last 20 years as a family of Mac & iPhone users, we've gone through multiple Macs and iPhones and accumulated a terabyte of photos and videos.

I pay for the 2TB iCloud storage for the family.

We have a NAS in the home (Synology) with 20 TB storage with some additional photos in folder structure plus 9 different iPhoto or Photos libraries.

I'd like just get all the photos into one iCloud library in the cloud but as some phones are synced (and none of the computers has enough space to play around with a TB of files), its really confusing and a mess. I think even if i were to export in order to try and merge these libraries then backed up, they'd all be trying to sync and everything would run out of disk space.

I'm guessing there isnt a way to do this so maybe this is a feature request, but i'd like to have some of our photos in a central iCloud library thats some sort of "archive" that i dont have to worry is going to try and sync onto my current iphone. i also would like a way to upload old iPhoto libraries do the iCloud platform so i can organize, remove duplicates, etc. is there a way to do either?