Lumafusion (the incumbent product in this space) can edit directly on an external drive without copying the information to the ipad itself. I use a 4tb samsung

Lumafusion (the incumbent product in this space) can edit directly on an external drive without copying the information to the ipad itself. I use a 4tb samsung ssd and on usb-c , it's pretty much as fast as you need it to go, and if you need more space, you can get 8TB ssd's - it's more expensive, but it's easy enough to get.