AirPods and iMessage, agreed, never had a problem. The Home app though remains Apple's unloved ginger stepchild - every major OS release I'm hopeful that they've done something about it, but they never do. I'm starting to think Apple's internal view of Home / HomeKit is that they wish they'd never built it in the first place.
This is tough. Most home devices are built to be absolute bottom of the barrel. Notice that almost every HomeKit device says it only uses 2.4 GHz Wi-Fi?
Apple tried to do certification for a while in 2018ish, but nobody could get through it, so I think they stopped.
Apple is starting to build their own home devices and I expect them to eat the market and cause improvement via competition.
HomeKit certification is still a thing if that's what you're referring to. You're very much right about the bottom of the barrel nature of home automation devices though. Most of mine are about as good as you can get though (Philips Hue etc.) and the Home app is still appalling. Even if all the devices I have attached worked properly and did what they're told when the automations run, there's still some absolutely basic functionality that people have been waiting years for, like being able to switch cameras from stream only to stream and record via an automation - think "when I go to bed, I want the alarm on and the cameras recording".
I hope they do. I use only the basics of HomeKit, a couple switches and CCTV. I'd like to expand and use it for more stuff. So it's important Home is stable.