Yes exactly, it’s opening a chromium browser. I believe I can embed an API inside the PyQtWebEngine code to add this functionality, but you’d need to manually edit the HTML with some Pythonic API calls.
The Python code for this project I have published as open source, found below. It sounds like you are technically minded, so maybe it would help you to take a look?
Inside the python code is a large block of text as a variable. This block is what is run to boot the HTML file - the code around it runs as a wrapper to install this “python file as a variable” along with your html file and assets.
I hope this is helpful!
Once my uni exams are over in late Jan, I will work on the update and add the suggested functionality.
Oh - you can also manually set the geometry and zoom if you’re editing the code :)