It’d be really cool to be able to use Listary to search these services as well, but only when prefixing the search with something (i.e. to search for an email in Gmail do something like: “gm appointment scheduled for”, which would open the browser & gmail to that message when clicked). Same for the other services, but obviously using the proper security/privacy protocols in the process, most likely making use of the API’s, etc. 
It’s a good idea to create a plugin for this (plugin support will be added in Listary 5).