Congratulations on getting Homebridge built.
As you move into the Hubitat Universe you'll find that Raspberry Pi will be quite handy. First, Hubitat has community built connectors to Homebridge. You activate/enable/install a built-in App called MakerAPI and add the matching Homebridge Plug-in on your rPi. Then, devices you select on Hubitat will show in Apple's Home App.
Your Raspberry Pi (rPi) can also run Node-Red, which is a tool for visualizing automations. It also uses a MakerAPI instance to send device actions (events) to and from Hubitat.
For voice announcements, Hubitat has a Google Chromecast driver, and so does Node-Red.
There's a cool rPi image to boot a rPi with both Homebridge and Node-Red installed and with the plugins added already too. Raspberry PI Image for Homebridge + Node-Red
I must admit to not knowing anything about "Google AIY Voicekit" BUT I am using a Google Home Mini as my announcement device with MP3 sounds and TTS. The majority are via Node-Red now, but all of it began with the Hubitat Chromecast driver.
There's a great topic on Node-Red Samples that should help with ideas on how to join it all together.
