I also use my guest network for the (notoriously insecure) IoT stuff. Oftentimes I’ll take it a step further and use my PiHole to block whatever servers they’re phoning home to.
A good example is my smart TVs. My TVs are the single most blocked devices on my network, by far. Like on a day of heavy use, my phone or PC may generate ~2000 blocked requests. On an average day, my TVs generate 7000+ blocked requests. That’s ~5 attempts to send telemetry data back to the mothership per minute, even when they’re not in use.
This is actually backwards. Texas Instruments made so many bomb chips that they ended up with a surplus. This allowed them to throw those chips into calculators and edge out any competition with lower prices (because they already made the chips, so they weren’t paying for them.) Then once they had run off all the competition, they jacked their prices up.
And that, kids, is why the TI-84 costs $100. It’s tech that costs all of $10 to make and program.