Is there a way I can turn off messaging entirely for child xbox accounts?

Only the one who turned on the child's account can turn it off through their main account.

I know this is a VERY old thread, but why does xbox want you to turn off NAT? I understand it can interfere by hiding the IP address, but turning it off just exposes your entire home network. Is there a way to open a port just for your xbox?

On a different pc entirely I can confirm that I do see the permissions message.

I've tried turning on/off any firewall permissions, any web adblock and even made a new admin windows account and it still won't show.

Child accounts can't purchase/download rated content above their age (T for under 13, M for under 18), or unrated (Indie) games from the marketplace. They just can't and there is no way to turn this off on a child account. You'll have to use an adult account
to download the content or wait till you can promote your account to an adult account.

I believe that a child account, by default, has purchases options turned off....you'd need to change the Privacy settings on the child's account to allow purchases.

You can manage things from the Xbox Family Settings App but I am not sure which option turns purchases on and off

Edit: FOund this on an older thread from someone wanting to upgrade Xbox Live to Game Pass on a child acocunt:

"I figured it out for my child. I had to go in and allow them to buy items without asking for my permission. Once that was changed I logged into their account and converted the subscription to game pass. Afterwards I went back into my account and turned on the content restrictions again."