I’m glad you’re not expecting an easy answer. 
The first two of these work and can be stable, the third only exists in a dream. Depending on what you have, the cost for this can be as low as 20 quid for just a Mijia Multimode Gateway, although I would opt for the Aqara M1S instead.
I bridge Xiaomi Aqara and Mijia devices with HomeKit automations, so yes you need two additional hubs, and a RPi or computer to run Homebridge or Hoobs, but in my case I watch television on that Apple TV 4, and we’re an iOS family, and Mac users, so that works out for us. I also already had Homebridge and other node.js applications running on a separate computer long before I got my first HE hub.
If you are an Android wielding family, then it can be done with HA and a few simple automations to sync back to HE, where you can use them as if they were directly connected (almost). Just as my method with HomeKit automations excludes variables data from devices like temperature sensors and vibration sensors, so too does this. But I have found those two Aqara device types to actually stay paired to Hubitat quite well when the repeaters are in the right place. One Xiaomi hub and a RPi 4 or a spare computer, and patience will do the trick.
If I have my second wish granted (My first arrives today at 11:59am EST), then it will be to have a HomeKit Controller type of app in HE so anything that can connect via HomeKit (which is just about everything) can bring its devices into HE.
No there isn't a lot of cohesion yet. It's moving in that direction, but slowly.
