Intuitively, I am missing an ability to navigate around the items with my keyboard.

Be it the arrow keys, vi's "HJKL" or the forsaken "WASD" for these pesky gamers (guilty). Holding the Shift key, whilst navigating between these items, could intuitively multi-select them and an Escape key could cancel the multi-selection. And I'd assume the Delete/Backspace button could do just that - delete an item(s) selected.

Without going crazy and implementing pretty much anything anyone would ever ask for (don't default to WASD or HJKL), I do believe there are some fundamentals that could be implemented into - well, not only Proton Pass, but frankly any of these desktop/web apps.