The only smart devices left are some smart bulbs, and I'm waiting for them to fail before replacing them with regular LEDs. Nothing beats the reliability and energy/resource savings of plain locks and buttons.
If you look beyond the consumer-grade trash, you can get somewhere nice with $500 if you go the DIY route with modules/relays supporting open protocols and Home Assistant, or if you have several thousands to spare check out higher-end solutions such as Crestron.
Any good system will be completely self-contained, not rely on the internet, and provided the hardware is maintained should last essentially forever.
Unless you have free spare electricity, I think it’s very difficult for smart electric lighting to be environmentally friendly. The controllers simply need too much standby power.
For example, https://eprel.ec.europa.eu/screen/product/lightsources/84743... is a 5W IKEA lamp that uses 0,3W when powered off. So, the lamp itself uses 4,7W, and you can leave that light on for about 1½ hour every day for the power that the controller uses. Said otherwise, you currently have to have such a light on longer than needed for 1½ hour every day to make up for the energy use of the controller. Add in energy used to make the controller and it gets worse.
There are days where I accidentally leave on a light for 1½ hours, but that’s nowhere near the average over all my lamps over a year.
Smart lights give you convenience. They won’t help saving the environment.
https://www.youtube.com/watch?v=UiS27feX8o0
To me, this really shows the sad direction smart appliances have gone in. I would love to see that smart appliances would have continued to evolve in this direction. I don't like the current state of smart appliances, but going back to the absolute basic seems like an over-reaction to me.