Set up a pihole on your network and add a few block lists. If your IoT appliances phone home at least you can block the traffic and monitor what things phone home.
As for buying appliances that are not smart, It takes extra effort and a trade-off in features.
For example, my toothbrush has Bluetooth in it. if I want a non-Bluetooth toothbrush I’d have to get a lower quality model because they simply don’t make one without it.
Most people buy whatever’s on sale, And considering how expensive home appliances are they usually put the expensive featured models on sale since there’s a bigger margin.
So if I wanted to get a basic one with less features, that’s not smart it would actually be more expensive because it will never go on sale.
How dare they! /s