I’ve been toying with smart home products for many years. I have friends who get deep into home automation - the problem is often that their spouse often can’t operate the system so is ‘stuck’ ( and frustrated) trying to get even the simplest things to work.

I would suggest dipping your toe in the water rather than trying to dive in all at once. The most useful smart home tool I have are smart plugs which I use for our regularly used lamps as well as a few other things like our printer, shredder and Christmas tree and topper.

The things I choose to automate are the ones we typically turn on and off daily or multiple times a day. Most can be usefully scheduled to go on and off automatically (i.e. on at sunset off late in the evening). In addition to scheduling I also connect these to smart speakers (we use Amazon Echo aka Alexa, but there are others) so we can also control them by voice at will (i.e. “Alexa, turn on the printer” which is at the other end of the house). I have also created a “Bedtime” routine so when we’re heading to bed we can just say “Alexa, turn on Bedtime” and all of these things will immediately turn off (you can also build in a delay).

Starting with smart plugs have a number of advantages. One is that they are cheap and easily moved around when my needs or desires change (no wiring, etc). Second, most just work off an app so there’s no added complication of integrating with a hub. Third, when I move I just take the plugs with me and use them in my next house - with no inconvenience for me or the next owner.

I’ve been doing this for years and have added a few other items here and there like smart bulbs where I need scheduling but can’t use a smart plug (i.e. porch lights) or dimming. In thise cases I use the same brand so I can control everything through a single app (I use tp-link). The new “Matter” protocol should hopefully make different brands more compatible, we’ll see.

At the beginning I was envisioning a total smart home but the smart plugs and bulbs have taken care of 80% or more of my needs with minimal investment and very little complication or frustration, so I now have no plans to go further. I like convenience and I like simple and I now have the best of both worlds.

You may already have this, but first step would be to make sure you have very solid WiFi coverage throughout the house. That may require a number of APs scattered around, preferably hard wired instead of meshed.

I highly recommend going with “if my grandparents can use it without issue then it was a success”

Homeautomation is supposed to make your life easier not harder.

There’s a ton of things I could recommend but it comes down to what is it I’m trying to solve?

For me lights being able to turn them on and off at the switch and through automations. With the above if grandparents can’t use it then I failed. I have motion sensors once tripped they turn on occasionally they lag which needs a restart. (Just the automation not rebooting.) I also have the ability to use an NFC tag to open my garage and turn on the lights.

There’s a lot which I’d like to do but I’m content with where it’s at for now.

Home assistant which is highly recommended here isn’t for everyone it’s getting better, in fact has made major strides lately. I’ll admit I don’t use it to the full extent. Mainly because I lack in the skills. It’s journey and can be difficult hobby at times.

If you do go this route please avoid a RPI they are great but not worth the expense you can get so much more in a SFF or NUC. Even an old laptop will work better. But if you must DO NOT BUY AN SD CARD they will die. Use an M.2 or SSD USB to SATA.

To your question HA works with HomeKit. (Bridge) easy to setup too.

Last crazy thought you will discover a lot of your devices show up instantly. I was truly amazed at what showed up. For instance my toothbrush. (Bluetooth never use it though).