According to that site you can downgrade the firmware (some people really disliked the various UI changes and the firmware is getting quite prescriptive)

You can also run your own homebrew apps so I found someone who installed KOReader which they claim is better experience than default reader especially for pdfs and also link better to personal cloud storage.

There’s also ability to use locally stored Web Application Frameworks but I’m not 100% sure what the use case would be.

I read something about how the best outputs are done using a blend of make-up/models with CGI adding the layer of realism on top so pure CGI is worse but film studies pursue that because its cheaper and outsourcable compared with a heavy unionised make-up/prop workers.