It’s difficult to say for sure and some hogs do apparently dig a bit, but unfortunately, it sounds a bit like a rat to me. If it is a rat, I imagine it would be going in and out, unless there was another hole nearby. So you could put something in the entrance, i.e. a leaf, some rolled paper, and see if it moves. If it was me, I would leave it alone, in case it’s a hog, unless I actually saw rat activity there. It is one of the drawbacks of having hog boxes without bases. Rats do like digging holes and create a surprising amount of soil and it would be quite tempting to one having a sheltered place to dig a hole.
One way to check if you don’t have a nightcam is to use a footprint tunnel and see whether you get rat or hog footprints. https://www.hedgehogstreet.org/footprint-tunnels/
Sorry, I know that’s not what you were hoping to hear. But it isn’t a certainty. Maybe a bit more investigation required. I hope, for your sake, it turns out to be a hog.