Why can't the browser manage site personal data in my solid POD?

I’m an artist, not a coder so this might be a really dumb thought, but currently as I understand browsers hold site cookie’s and local storage for sites; would it not be a good idea to be able to link my POD to my browser on my device, then when I visit a POD driven site, my site data etc can be stored on my POD for me; then, importantly if I need to manage my data for a particular site, I can view and do that securely through the browser UI.
From a web designer /developer perspective, a user visiting their site and who have a linked browser-POD; the JS site code could then use some native JS command equivalent like localStorage to work with users POD data, but in a controlled standardized way?