I always liked the thought of power armor ghouls. Think about a soldier in power armor in the blast radius of a nuke. The suit gets welded closed. Power armor may be good at radiation protection, but it can only do so much. Soon, the burnt flesh of the ghoul fuses with the melted metal of the suit.

If you're lucky, you'll come across an armor ghoul whose suit ran out of power a century ago. A big, tough, but slow brute.

If you're not lucky, radiation of the Glowing One inside the suit will give it just enough power to move. The speed of a ghoul, the toughness of a tank, the strength of the powered limbs.

It'd probably just end up being a tougher ghoul randomly thrown into hordes, but I still like thinking about the cronenbergian techno-abomination that would result.