-- a good starting guide is at https://www.freecodecamp.org/news/what-are-bookmarklets/
-- it's not clear what could be the best method for calling them with a keyboard shortcut (where relevant/applicable), but a few approaches exist: https://superuser.com/questions/387729/creating-hotkeys-in-f...
-- it's not clear how to automate applying one such javascript snippet on each page load of a URL of defined pattern matching - there probably exist at least browser extensions