Boarding parent here.
I have just had a long, hopefully honest, conversation with my youngest son, he's 19 next month.
We are having a Luther marathon (I cannot quite believe I've not watched this fabulousness before lockdown), however, between episodes we're having life chats.
He openly admits he missed us, I knew this already, he had his elder brother at the same school for a number of years before he left and is unable to say if this was a benefit or not. He formed close bonds with his peers and his teachers, clashed with some too but has already decided that if his children would like to, he would like them to have the chance to board.
Interestingly, he seems to confidently believe that if he had been unhappy, we would have let him leave and attend a day school. I don't remember ever conveying this, but what I gathered from the conversation is that he knew, and knows, he can come to us with any issue.
I'm in no doubt at all boarding does not suit every child. My children, who are adults now, genuinely loved it, warts and all.