Looks good. One minor suggestion, this part:
can be done in the GUI with a Custom Destination and Misc Application. You would create a Custom Destination using the exact same goto string PlayUSPSMailboxContext,OriginateSound,1, and then a Misc Application of 26670 referencing the Custom Dest. What you’ve done is correct, but perhaps less obvious to anyone logging in after you. Using the GUI also comes with some protection against using that dial sequence (26670) for something else.
There has been a bit of discussion here about automation and node red:
Fun with AMI (node-red)
Fun with AMI Node-Red 2
Open Source Pro Tips #9 - Connecting to & Controlling FreePBX with Node-RED: Part 1
Open Source Pro Tips #10 - Connecting to & Controlling FreePBX with Node-RED: Part 2
Home automation and FreePBX comes up from time to time on the OSS Lounge as well