Correct me if I'm wrong, but what you're describing is client-hosted Bedrock servers, not a persistent, always available, self-hosted server. AFAIK connecting to a friend's world in Bedrock is free, but they must also be online. Hosting a persistent Bedrock server is a paid feature (Realms).
Additionally, highlighting that Bedrock Minecraft is not supported on Mac.
There are surely other ways of enabling multiplayer Minecraft for a family than what I've described, but this is the way I'd recommend.
Unfortunately, Apple made the decision to have that be an opt-in flag for developers, and so the vast, vast majority of iPad apps don't allow themselves to be used on macOS.
Additionally, highlighting that Bedrock Minecraft is not supported on Mac.
There are surely other ways of enabling multiplayer Minecraft for a family than what I've described, but this is the way I'd recommend.