I read a lot of posts on Facebook about how specifically during mealtimes their kiddo on the spectrum cannot sit still. Sitting still is not an easy task for a child with ASD or SPD to begin with in some circumstances. But eating can make it even more difficult for that person for a number of reasons. It can be anything from the excitement of eating or a way to actually focus on eating by removing yourself from the situation & restarting yourself in between each bite. It can be overwhelming sensory wise from smell to texture. Maybe it’s a combination maybe it’s an isolated sense. But note there are many reasons that it might be difficult to eat during mealtimes in a seated position. And generally wanting to ruin mealtime is not one of them.
Movement or vestibular activity helps aid in concentration and focus and might help a person who has a hard time sitting still during mealtimes. Additionally, it can help you focus on other tasks too. A therapy ball chair on a stand is my favorite thing to recommend to people. You can use a stand alone ball but it’s better to get one on a stand so you don’t fall off or wander off with a roll in your mouth.
Heres a picture of it.

Here’s a link to find it on Amazon.
Give it a try.