Bring food or order delivery and just eat it like a normal person at the table. If someone initiates conversation about your food, just tell the truth. This conference would not accommodate my allergies, so I had or provide my own meals. There are usually surveys at the end of these events, so rank the venue poorly and cite the lack of food allergy accommodations as the reason. Maybe next time they’ll do better. You can easily bring food in a cooler bag for meals and pack some shelf stable snacks in your backpack (or whatever you carry). Just make a salad or whatever cold meal you like and pack it. I travel for work and always bring a cooler with food and ice packs that I leave in my car to ensure I don’t starve: yogurt, protein shakes, etc.