We only fly Delta. When we needed assistance due to mobility issues, we always notified the airline that we needed a wheelchair with assistance to the next gate. There was always an attendant and a wheelchair waiting when we landed.
As far as assistance through the lines at TSA, we never needed that. I wonder if you can prenotify them of a need of assistance, like the airlines?
I hope your future flights go well.
Yes you can pre-request assistance from TSA.
From the page @
https://www.tsa.gov/travel/passenger-support
TSA Cares — Passenger Assistance Requests
Contact TSA Cares
(855) 787-2227
Federal Relay: 711
Weekdays:
8 a.m. to 11 p.m. ET
Weekends/Holidays:
9 a.m. to 8 p.m. ET
I have only had one bad experience on Delta out of 50+ interactions over the past 5 years. I have flown out of or thru SEA, SLC, LAX & TUS to name a few.
Delta Airlines — Disability Services
There is a phone number at the link above… call them to have your needs notated on your reservation,
for all legs of your travel.
Save that number in your phone, and if you need assistance at the airport & have difficulty or feel like your needs aren’t being met for anything not TSA related, call them & they will help you in real time.
If you have trouble with any TSA interaction, calmly and politely ask to speak to a supervisor, and ask that your party be moved to a private screening area to await their assistance.
It is *always* your right to be screened in private, although it will be a more “hands on search”. Sometimes though, it creates less anxiety and ends up being easier in the long run.

If you use social stories, perhaps you can make or find one that deals with airport screening & appropriate behavior in the airport. There are also videos that show what happens at the screening area, if that might help you explain “what kinds of things might happen to keep everyone safe on the plane.” (<< This is how we worded it to our ASD kiddos to help them understand
why their stuff had to go in the x-ray tunnel, & they had to walk thru the metal detector or body scanner. We also practiced how they’d go into the scanner & stand still with their hands up & count to 3)
Good luck & safe travels. Have a fun trip.