I was fortunate that there was usually one or two other JW kids in my classes early on. So I wasn't the only child who sat at his desk as everyone else stood, or who was asked to wait outside in the hallway while the rest of the kids recited the pledge. It wasn't traumatic, at least it didn't seem so at the time. But I did become a quiet kid who mostly tried to stay in the background, invisible.
I don't remember if other kids asked about it. For the most part, they probably thought we were wierd but didn't care much. I am pretty sure we weren't bullied for it. This would have been the mid-70s, and it was a different America from the 40s, 50s, and early 60s.