Are there actual plugin authors that want this, or that are even interested in distributing their plugins via pip/linux distributions, or are willing to add the necessary metadata to their plugins?
As per
https://calibre-ebook.com/dynamic/calibre-usage there are under 5% of calibre users on Linux, which is really the only platform where this would have even a chance of being used.
In order for me to consider this, there would need to be some demonstrated interest from plugin authors.