The firmware for the devices is open source, but the apps are not open source.
That's exactly why I absolutely refuse to touch it. Until somebody makes an open source app for it, you won't catch me using it.
Discussion
Yes, the apps for meshtastic and the firmware for meshtastic is open source. The firmware for mesh core is open source, but the apps for mesh core are not open source.
Yeah, that's a pretty odd choice.