Here's the thing, and you should consider this an opinion, but it's not based on guesses, but knowledge from other companies that have done this. Commercial HomeKit licensing is expensive. So do I want Hubitat to sink their limited resources in paying Apple licensing fees for HomeKit commercial use? Big fat NO!
Adding Homebridge is simple and it's cheap for the end user. Something is wrong in your setup if it's unreliable. I have been using Homebridge with @dan.t 's MakerAPI plug-in as @aaiyar mentioned, for years. It should be working perfectly. If it's not then you have something wrong on your network and/or the computer that is running Homebridge.
With Apple HomePods as the hub, you can expose virtual switches to Homebridge and sync them to devices that are exposed to Homebridge, but are not directly HE compatible. To simply control devices that are already in Hubitat from Siri, you simply expose them to Homebridge, and then add Hombridge to HomeKit as an accessory, allowing all devices in Homebridge to be exposed to the HomeKit cloud.
Now if you're expecting to be able to get measurement data from things like temperature sensors that are HomeKit compatible, but not directly HE compatible, then you cannot do that with Homebridge. I would instead look at this project that will allow the use of HomeKit Controller in Home Assistant and bring those devices into HE. If you wanted to, you could potentially eliminate the use of Homebridge by also exposing devices from HE back to HA with this second integration and then use the HA HomeKit integration. That is different from their HomeKit Controller integration in that it exposes devices to HomeKit, rather than acting as a HomeKit bridge.
Both are simple to setup, and frankly although I find HA difficult to automate in, the good thing about the HA to HE integration is you don't have to. In fact, whether you're using the HomeKit controller integration or joining devices directly to HA to get them back into HE, it's only when joining a device that you ever need to touch HA. Setting up HA on a RPi or a virtual machine running on spare computer is very simple because they have created a ready-to-use image.
So you may be wondering, if HA can add HomeKit integration, why doesn't HE just do that. Well they could, but it would cost them a lot, and in turn it would likely either drive the cost of the hub higher (nobody wants that), or it will rob valuable resource from a small company for little benefit versus the easy to add Homebridge or HA. Since HA is an open source project, they fall under the non-commercial use category and so don't have to pay anything, and don't have restrictions. Same with Homebridge which uses the HomeKit APK. Although, I wonder about that long term, as HA does sell a version already installed on an ODROID-N2+, which constitutes commercial use, so they're actually breaking the rules a little.
I have a Thermostat and have a Homebridge instance dedicated to it. Mostly I just wanted to understand how-to and now I know. 
