I simply won’t install anything that doesn’t support a local API. Happy to pay for the hardware; but if your plan is to monetize it via cloud services somehow, or just assume planned obsolescence, I’m not your customer.
If your device requires, in any way, an internet or cloud connection, even just for setup, it doesn't exist for me. If you have some FULLY OPTIONAL services I might like as a SAAS free or subscription option, ok; but the device MUST 100% work without ever knowing your cloud exists. It must also be designed to fail-safe and have manual fall-back operability (e.g., when the power goes out, I can still manually switch its state to OFF).
I recall an article or comment on HN talking about the advantages of a "MidWit Home", devices that weren't really smart, and just had remote control. I've got a bit of that with some remote switches to use around the house with enough range we can turn on from the car when arriving home. Also timers. Seems like a good way to go.
I haven't made a vlan yet for IoT stuff because my ISP's router do not let me, I can't wait to have my own openwrt / opnsense router and put the ISP in bridge mode.
That advantage of this is that some ISPs will try to blame your router (and your modem if you are using your own modem) for any problem you call in about no matter how obviously it is a problem on their end or with their equipment. This way it is not obvious to the tier 1 tech support people that you are using a different router.
I suppose if you want to be really thorough leave the wifi on, either with whatever the default network names the ISP router starts with or with names that don't match the ones you really use which are on your router.