Apple Laptop Mini or Desktop Monterey 12.0.1 Largest HD Size available

So let’s look at this a bit differently… You want something that is Mac compatible which can support internally massive/s drives. You are looking for iPhoto server so you don’t need the drive be in your running system just accessible via a network connection.

There is two approaches you could take, the first is get a 2012 MacMini server which offers two SATA ports and then plug in SSD’s. macOS Catalina 10.15x is as high OS it supports, but that won’t matter with your other system which can be running Monterey over the network connection. I have this setup for my media server with two 2TB SSD drives. There are much larger SSD’s available like 16.0TB OWC MERCURY ENTERPRISE PRO but its quite expensive! I would go with Samsung 870 QVO 8TB getting two is still cheaper than the single OWC drive!

The other direction is to get a NAS unit like a Western Digital My Cloud EX2 Ultra

And lastly if you need fast I/O and still bigger than you’ll need something like: 40TB OWC THUNDERBAY 4 - RAID 5 connecting it to your newer 2020 MacMini externally.

I wouldn’t go with traditional HDD’s anymore, while you can get larger spinning rust drives, you will end up needing to do yearly housecleaning as the drives get fragmented as you use them so they get slower and slower as you use them (which is not the case with SSD’s).