Regarding coding, it sort of depends - if you build lights driven by WLED, it can be as simple as getting the parts together and visiting a website. (There are now even plug in, no solder boards you can buy.) But there are some platforms such as HomeSpan, where you more or less configure the whole thing from the ground up and it can be involved.

The hardware requirements are sort of piecemeal, but all of my home automation stuff - microcontrollers, sensors, switches, etc, all fit into a relatively small toolbox (and a totally messy workbench). Most components (aside from tools) aren’t super expensive, but LED strips and power supplies can get spendy.

I’ve been doing smart home stuff for a while, and have a slew of systems that, well… many years ago I didn’t think about how they leaked my data, or really cared how easy it was to integrate things. I’d just install a new app, throw a new bridge onto my network, etc. After a while, the question of what device is on what app, or if this sensor can trigger that action/device is burdensome.
I get a lot of satisfaction out of reducing the complexity of my digital life, and knowing that there’s less vulnerable points within my network (and less data about me leaking out).
Life, and the business of living is really challenging. My wife and I have ADHD, and being able to reduce even minor burdens frees both of us up to focus more on just living. (And sometimes it’s just fun to have rainbow swirly lights!)