Supplements are things to be added after the horse is full time on a proper base diet, which is at least full time good quality forage.
If this horse is a low BCS 3, or less, then you really need to follow something like that UC-Davis re-feeding program, as excess nutrients too soon for those horses can cause Refeeding Syndrome which can easily kill them.
Fast weight gain is not your friend.
The best 'all around" anything for this horse is going to firstly be good quality hay, to include as much horse-appropriate (as opposed to dairy quality) alfalfa as you can get for the Winter.
He doesnāt need a hoof, or coat, or energy supplement, before he settles into getting back to eating like a normal, healthy horse, which is free choice good quality forage, and then, if he needs more, a ration balancer or high quality low NSC regular feed.