Bubs

It’s nothing dystopian like you think. Basically just a variation on camera sensors:

[…] bio-inspired cameras that capture the world more like the human eye does. These are called dynamic vision sensors, and they work like motion detectors for each pixel. They only “wake up” and send information when something changes in the scene, rather than constantly streaming data like a regular camera.

These bio-inspired cameras are also highly energy efficient, using less than 1% of the power of normal cameras.

Took a quick look at the free tier,

• 3 users
• 100 devices
• Basically all tailscale features

That seems pretty reasonable to me. Main account and two accounts to share. With just friends and family, I doubt most people will reach the 100 device limit.

TL;DR from Wikipedia: In photon upconversion, two or more incident photons of relatively low energy are absorbed and converted into one emitted photon with higher energy.

Basically photons are combined into a photon that is nearer in wavelength to visible light.