I think the answer is “Yes” to both your questions.
I would love to get a Homepod with a screen, like an Echo Show. A device like that, running tvOS, could sit in my kitchen and be a Homekit hub, Thread border router, and also be able to do Facetime, Apple Music, Apple TV+, and pretty much everything else an Apple TV can do. The speakers don’t need to blow the doors off the place…just a nice sound similar to a Homepod mini.
The answer to your second question is also a “yes” because that communication between hubs and devices has been so hit and miss over the years that it makes it super hard to recommend Homekit to anyone. There are days when it is flawless and then the next day there’s all kinds of issues, for no apparent reason. Every year we hold out hope that the next iOS cycle will make it better and it always seems to fall short. I’ll keep hoping, but at this point, a person almost has to be happy if commands are successful most of the time instead of all the time.