I don’t know about the 13, but on the 16 you can update via USB, no OS required. Kind of annoying, but it works.

https://www.sensorwatch.net/

Yep, the captchas are great. I’ve got mine set to an NFC card in another room. It forces me to get out of bed and walk to another room to tap my phone on it to turn off the alarm.

It is, but as far as I understand, you can disable some of it depending on your coreboot/libreboot setup.

Coreboot is open source, but when you build the rom for your machine, you have to pack in closed source blobs for Intel me, and any other proprietary parts of the chip.

I’m not up to date on current happenings with libreboot, but the goal there was to get it working 100% open source, without closed source blobs.