Hi Sarah,
if she is particularly food obsessed you or your OH could try feeding her something extra special like roast chicken or cooked offal from a partially clenched hand so that she can just and no more lick and pick at it, thus keeping her occupied while the other of you is administering the treatment at home. If she is very apprehensive of treatment , however, she is unlikely to favour food over her fear of what's about to happen

If any of my dogs are unsure about a situation then there is no way on this earth that a treat (partcularly from a vet or complete stranger) is going to work.
If you can get the treat system to work at home then by all means try to take this a step further by including it in her vet visits but don't push for too much too soon otherwise you'll have blown it

Establish her confidence at home with yourselves first and then gradually work towards dropping into the vet office occasionally and having her petted, fussed and given her special food treats while the nurse (or vet if available) is doing something simple with her like checking her paws

TBH if she's particularly phobic about veterinary treatment none of this may work but the main thing is that her character is otherwise good so should a muzzle be necessary occasionally it is not the end of the world

best wishes, Teri