The hub-to-hub communication feature in Pybricks MicroPython is not restricted to LEGO hubs alone. I just released a new library that enables simple wireless communication between any number of MicroPython boards that support Bluetooth Low Energy (BLE). This includes LEGO hubs, but also other boards like the Pyboard, the Raspberry Pi Pico and some Arduino boards.
If you just need to send small amounts of data, this can be a lot simpler than setting up dedicated connections between the boards. This can also be a great way to interface with other hardware, such as Arduino boards with all kinds of accessories.