I have a severe Peanut/tree nut allergy I always fly with multiple epi-pens on hand. Flying down with Southwest they were great they gave me pre-boarding to wipe down seat and they give you a special boarding pass to give to flight attendants. Nothing was served with nuts on the way down and had a great flight down. Also, bonus info- cruised Carnival for the 7th time they handle allergies very well FYI.
Our return flight back we flew Jet Blue and they were fantastic. The gate was well aware of my allergy before I boarded, so I had time to wipe down seat as we had preselected. They made an announcement to the area around my seat, as it wasn’t a full plane the lady in our row moved which was fine the flight attendants were great. They even had peanut free cookies as snacks. It was a great experience on both flights.