OK, I got a realtime GUI "proof of concept" working on my Linux workstation.
It uses Python and Libre Office Calc and a web browser.
The spreadsheet is a text document in SYLK format. It is attached as input_file.slk.
The Python script is attached as SylkRenderer.py
Save these files and open input_file.slk in a text editor.
In a terminal window launch a headless instance of LibreOffice Calc with this command: