Yeah, I would not suggest DIY'ing anything that's directly connected to mains power unless you are super sure you know what you are doing. That's a really good way to cause you problems with your homeowner's insurance if you have a fire and it could be against your local building codes.
That said, there are devices out there that can be used on mains power that are UL certified. I have a ton of Z-Wave [0] switches and relays for various things all talking to Home Assistant. Z-Wave is an open [1] (or soon to be open) mesh networking communications protocol that is pretty widely used and supported, so you're not locked into a single vendor.
For low-power stuff, I'm a bit more willing to experiment, but not on mains power. But I am also not an EE. :P
That said, there are devices out there that can be used on mains power that are UL certified. I have a ton of Z-Wave [0] switches and relays for various things all talking to Home Assistant. Z-Wave is an open [1] (or soon to be open) mesh networking communications protocol that is pretty widely used and supported, so you're not locked into a single vendor.
For low-power stuff, I'm a bit more willing to experiment, but not on mains power. But I am also not an EE. :P
[0] https://en.wikipedia.org/wiki/Z-Wave
[1] https://www.theverge.com/2019/12/19/21029661/zwave-open-stan...