How to prevent accessing devices of other users?

Today I’ve started testing Firezone with one user and added 2 devices to him. 1st device is a Raspberry using my mobile phone hot spot and 2nd device is my Laptop.
Now I’ve added a 2nd user with one device and imported the config to my Laptop. After enable this device, it can access my Raspberry for user1. Isn’t this a security issue?

What if this feature is added: Allow overriding the server-side generated AllowedIPs for a device. · Issue #567 · firezone/firezone · GitHub

Let’s say one Raspberry is in the home of my brother with network and a 2nd Raspberry is in my home, also with network

Creating one user for my brother (user1) with 2 devices (Raspberry and Laptop), one user for me (user2) also with 2 devices, how will my brothers or my Laptop know what’s his/my network?

Thank you.