You can also use this. I''m using this method for door announcements. You don't have to have Google Assistant Relay, since you can do it with the method outlined by @keithcroshaw using OtherHub2, but if you do decide to do it with Google Assistant Relay, then you have both methods available.
I actually still use Google Assistant Relay to do the laundry announcements and for laundry status (which machine is running), but could switch it to Alexa just as easily.
Do you have an old laptop you could use? I'm actually using an old Mac laptop I have configured to stay awake when the lid is closed. Quietly runs all extras, not very high power consumption either. I'm running Homebridge, Google Assistant Relay, VLC Player (for use with VLC Thing), and Insteon-Server (a Node.js server to integrate Insteon with Hubitat) on it. You can certainly do all that with a Pi, but I had a few of these 2009 aluminum MacBooks given to me and they work well for this task. I'm a Mac user for my primary laptop, so this makes admin very simple by using the built-in screen sharing of Mac OS. But any VNC will work with a Pi or Windows PC too.
