I would give low level webdrivers a go. But so far I have not even figured out how to install one for Chromium on Debian.

    apt install chromedriver

gives me:

    Package 'chromedriver' has no installation candidate

There is something called "chromium-chromedriver".

Let me try that ... one moment ...

Ok. So I start it via:

    apt install chromium-chromedriver

Now according to the docs, this should create a browser:

    curl  -d '{ "desiredCapabilities": { "caps": { "nativeEvents": false, "browserName": "chrome", "version": "", "platform": "ANY" } } }'  http://localhost:9515/session

Ha! It works!

So chromedriver might be a solution!