...we are flying J to EWR on 2/4 with and ASD child who can tolerate a little queuing and a hearing impaired child who really struggles when it’s crowded and noisy.
I feel your pain. Last year I put together
a rough guide to flying with children with SEN, but most of it assumes that airport and airline operations are functioning more or less as expected.
Sunflower lanyards are hit-and-miss: sometimes they're helpful, sometimes they're not. I think the key is to hope that they will be beneficial, but not to expect it.
Based on previous experience, my plan would be the usual stuff you probably would do already: make sure all electronic entertainment is fully charged, get the kids to the toilet before getting in the queue, then just give them headphones and try to block out the world around them. Whatever works.