That HD+ Device driver is broken
That would be interesting to see what it could come up with. But, really it's not just a matter of writing the code -- sending FCM (push) messages is designed to be sent from a single server. One of the FCM changes required (V1) is to use OAuth which means I can't just use a shared server key anymore. It wasn't the right way to implement it originally either but I was trying to make it as simple as possible for anyone to use.
Ultimately since we all own our own servers (Hubitat Hub), this is going to require an app+driver combo similar to the Google Photos app.
But, the good news is I've been working on this for a while now and I think it's getting close. Assuming it works I'll try to document the steps and then see if anyone can help try it out. It'll require some setup work but hopefully I can make it as painless as possible.
for anyone reading this and not sure what I'm talking about.. this is for an optional Hubitat driver that can be used with HD+ to do some additional features like push notifications, TTS.. it also has potential to do a lot more in the future