I looked at the photos of the stove on ebay, and I don't think burning pea coal would work anyway. The slots in the grates are pretty wide, and I think pea would just fall through into the ash pan. I see no reason that you couldn't burn nut or even stove size coal in this stove.
I don't see any form of hopper in the photos, maybe it is not installed, but a hopper is not actually a stoker. It is more of a big funnel feeding into the firebox. So If you got a chunk of coal that was too big in the hopper, it wouldn't break anything. It would just block a spot in the hopper's exit.
Right now the price is right on this stove, but I personally have some concerns about it.
First is that the seller states that a baffle plate is warped. That is another way to say OVERHEATED!! So I would be concerned that other parts have been overheated.
Next looking at the photos, I don't see a separate, devoted air intake providing air to the area under the fire. I only see the sliding air slots just below the front loading door. Unless there is some kind of air duct behind this slotted air intake, I don't think it will burn coal well at all.
And I also don't see any method to shake the grate to get the coal ash into the ash pan. You would have to use a metal poker with an 'L' bent on the end to rake through the coals and ash. This is necessary to keep the grate from clogging with ash.
If the price stays dirt cheap, you can install a 'spinner' type air intake in the front of the ash door to provide air under a coal fire. And of course you can get by without a shaker grate.
I think this is a better wood burner than a coal burner, but if you are handy and can fix it, it may be a bargain.
If you can, I would inspect it before purchase .