Pretty much anything automated boils down to setting a relay on and off, and also reading a value from a sensor. Most of these smart devices overcomplicate the hell out of it for nothing by requiring proprietary apps and worse, an online account and connectivity to a server you don't control. This adds planned obsolescence for nothing not to mention privacy issues. Anything smart phone based is practically guaranteed to be spying on you.
Been meaning to expand my own setup so it's more modular, the direction I think I will go is ethernet for each device that way you can easily use existing infrastructure. You can buy lot of off the shelf parts to impliment ethernet, some ports even have the magnetics built right in. I may go with putting them on the pcb separately though as it's better for servicing. Ex: if you have a physically damaged port.
I also need to make the wiring a bit, cleaner.
This has been running for a good 10 years now though. I did a few tweaks to the code over the years but overall it's been solid. Don't have to worry about any outside interference like some bad update, or spying, or any of that stuff.
If I need to adjust anything from work I just VPN in. I can still use my phone too but it's just a web page, so the OS does not matter. I use a custom rom so any of this app based stuff won't work for me. For notification it just sends email so I will get those on my phone using a standard email client. Again, no proprietary app BS.
Some ISPs are even now requiring an app just to configure the router, it's BS that everything is going that route. I had to setup internet for a family member and holy crap what a pain. Why not just keep it simple where you connect to 192.168.0.1 or something like seriously. That's the other thing, I hate that most ISPs are not giving dumb modems anymore, but that's a whole other subject.