Full disclosure: we know the owners of Jersey Mike’s. They’ll take care of you!
They offer Udi’s for their subs as well as subs in a tub (aka salad). Team members are well trained in GF options for subs. They put the sub on a piece of paper when making it so it doesn’t come in contact with surfaces that had our regular bread on it. They also wipe everything down, change gloves, and use special special knives to help mitigate cross contamination.
Depending on the severity of your allergy, they can also get separate condiments that have not been touched by gloves that have touched other subs before.