Your question is also asked all the time: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...

You can probably find many other posts as well by searching different phrases. Folks are always fishing for ideas via "Ask HN" posts.

A meta web browser, or browser toolkit. That is a web browser that by default obeys current standards but does not have to. It can be gutted or extended at the discretion of a user.

For example I would like to remove reliance on certificates for TLS. I know it’s a security nono but I don’t care. Another example is choosing to make markdown the default format instead of html.

Simultaneously such an application should allow users to add their own custom packages, such as native interpretation of Python or custom media codecs.