CREATING A STREAM DECK PLUGIN
If you don't have the programming skills (or time), you might be able to locate a skilled programmer at sites like https://fiverr.com. Though I didn't find a specific elgato programmer, any skilled programmer familiar with the requirements should be able to create an app.

Here's the rub though --- as mentioned in another PGM forum thread, there does not seem to be a scripting language or API for either BB or RB that we can leverage without the accompanying app.

USING BAND-IN-A-BOX REMOTE SERVER (BBRS)
PGMUSIC: https://www.pgmusic.com/manuals/bbw2020full/chapter13.htm

I suppose since this port seems to be bi-directional you might be able to communicate via this server, but without available documentation it would be a lot of experimentation.

In BB2020 under the [drive:]\bb\BBHelper folder there is a program called BandinaBoxServer.exe
Running this program sets up BB to receive commands via TCP port 7680.

On my MS/Windows PC this server shows up as LISTENING on port 7680.
  • [BandinaBoxServer.exe] TCP 0.0.0.0:7680 AQUA:0 LISTENING

1. Press: [Windows-key]
2. Type: Command Prompt
3. [Right-click] the Command Prompt App and select Run as administrator
4. Type: netstat -a -b | more
5. Press: ENTER

Using the "| more" option pauses the action.
The [BandinaBoxServer] info should be at or the top.

If one could communicate at least via the BBRS then at least we could script more cleanly.

How To Make Your Own elgato Stream Deck App
To create your own elgato Stream Deck Plugin, you will need these resources: