I was just looking at that. I also learned that the Ubuntu OS is still community driven and has ports for several common phones, like the Nexus and OnePlus One phones.
It's a relative scale. A binary blob isn't ideal from a security and privacy perspective, though given the nature of radio transmissions used with these devices, there are legitimate arguments in its favour as well. In any case, you're still much better off with a device where that is the only unknown factor than you are with a device where apps routinely spy on you and phone home etc.
https://docs.ubuntu.com/phone/en/devices/devices https://wiki.ubuntu.com/Touch/Devices