The biggest thing I see is the total lack of good muscling. With groceries and proper schooling, there will be definite improvement.
As for the training....there has been precious little, IMO. The horse does NOT know his leads. She gets them by cranking the horse into a severe counterbend which locks the outside shoulder. The only shoulder that can go forward is the "correct" shoulder. This will all have to be undone and retrained, unfortunately. However, with proper training, things would likely progress well.
I love his attitude when he steps all over the mounting block. Shows a good mind.
The riding with strong contact with a curb bit, only shows how green he is. Doesn't bother me too much.
He will be a slow project, at first. I would turn him out for a couple of months just to "detune" him and let him relax. Then I would forget any training he has had and start over from scratch.
He looks like a definite event project, pending vet check.