Seems like a lot of helpful comments and I don't have a lot to add.
But wanted to chip in that my DS (now 5) was not a fan of circle time up to about 4.5. Still complains about it as his least favorite times of day, but obediently goes now and doesn't bother the other kids. In some earlier preschools he would sit okay for a minute or two and then exhibit what I personally think of as normal for an energetic little boy forced against his will to listen to adults with fake happy faces singing songs or talking yet again about the weather (a subject that adults seem to be more interested in than most kids): leaning into a neighbor or standing up or wandering away or laying down and making snow angels on the carpet, talking, singing, just anything at all he could think of to avoid the desperate tedium of sitting still and quiet in one spot.
DS has some social ineptness but not to the point of aspergers/asd spectrum, and looks ADHD sometimes but not others. His challenges are more he is easily frustrated and emotionally tense/intense. Can easily focus and remain reasonably still watching a great TV show, or pay good attention for long periods of time to someone talking about a subject he's interested in. As he's gotten older he's gotten more tolerant of doing what others ask for the sake of pleasing them, gotten more used to routines, etc.
The turn around with circle time for him came when we switched him to a montessori/free-play preschool last year, they happily let him not go to their circle times for the first couple months (they were fine with him playing quietly within eyesight of the group), later let him bring fidget type toys to circle time, slowly transitioned to expecting more from him.
If you don't go with the public preschool perhaps there's a play based type of preschool your DS (or both your kids) could attend part time for the socialization aspect. Perhaps just for the segment before snack time or before lunch, picking up early and in that way avoiding the worst of the food allergy risk. Sometimes the least "best" preschools can be gems.
Polly
