It would likely be an NVMe or m.2 port, both of which I believe are much smaller ports that are standard on new motherboards that enable much faster bandwidth than anything over Sata. The most common internal SSDs that you can buy off the shelf and offer over 1GB/s read/write are going to be NVMe or m.2 drives (probably) and they're pretty fucking cheap, which is part of the reason people are progressively more upset about non-upgradable storage.