The thing I've most been convinced of in the past 5 years of building as much 'iot/smart home' stuff out as possible in my house is that nearly every vendor is selling crap that has marginal usefulness outside of a 'party trick' in isolation. Building out a whole smart home setup is frustrating unless it's all from one vendor, but there isn't one vendor which does all of it well for every need.
On my phone I have apps for: Ecobee, Lutron, Hue, 4 separate camera vendors[1], Meross, and Smart Life. Probably a couple more that I'm forgetting.
Only Lutron and Hue are reasonable in that they allow pretty comprehensive control to be done by a hub or HomeKit so I never have to use those apps.
It's been years since Matter and Thread were supposedly settled upon as the new standards for control and networking, but the market is, instead of being full of compatible devices, instead absolutely packed with cheap wi-fi devices, each of which is cloud-dependent and demands to be administered and even used day-to-day only through a pile-of-garbage mobile app whose main purpose is to upsell you on some cloud services.
[1] I admit the fact I have 4 is my fault for opportunistically buying cameras that were cheap rather than at least sticking with one vendor. But many people have a good excuse, perhaps one vendor makes the best doorbell camera, while another might make a better PTZ indoor camera.
Even if your hardware doesn't support local APIs, there's a good chance someone has made an HA integration to talk to their cloud API.
And if they haven’t, you can pretty trivially write your own and distribute it through HACS (I’ve got three integrations in HACS and one in mainline now)
My #1 wish would be for someone to build a HA-native voice assistant speaker. I'd pay $100 each for a smart speaker of the physical quality of the $30 Google Home Mini but which integrated directly with HA and used a modern LLM to decide what the user's intent was, instead of the Google Assistant or Siri nonsense which is like playing a text adventure whose preferred syntax changes hourly. I'd pay that plus a monthly fee to have that exist and just work.
or
https://www.home-assistant.io/voice_control/thirteen-usd-voi...
This M5 Stack ASR unit costs $7.50, and has a vocab of about 40-70 words. That's enough to turn on/off lights and timers. You might need to come up with your own command language, but all of the ASR is extremely local
https://shop.m5stack.com/products/asr-unit-with-offline-voic...
Sadly for family reasons I sadly can't take on projects that require more than a few minutes, so I'm holding out hope for someone to bridge the gap between the "project boards that require writing a bunch of code to interface with Home Assistant and define all of its possible abilities and commands" and "dumb as a post Google thing that you just plug in" with a hardware device that is easy to connect to HA and starts out doing what the Google thing can do, but smart instead of stupid like the legacy voice assistants are.