Naven
Answers
Can my school see my messages?
Not from the messaging service itself, unless the school administers the account. A school network can see which sites a device reaches, and a school-managed device can have monitoring software on it — that is a device question rather than an app question.
The distinction matters. A network administrator sees domains, not message contents, for any site served over HTTPS — which is all of them.
Managed devices are different: software installed by the administrator can see the screen regardless of which site you are on. If the laptop belongs to the school, assume it can.
Naven itself gives schools no window into student conversations, and its guardian relationship for under-18 accounts tells the parent nothing about content either.