People sometimes ask about having multi-character shortcuts for bookmarks; an easy way to achieve this, is by using an emacs package Hydra.
With Hydra installed, we can add multi-character shortcuts, for instance:
(defhydra my-mu4e-bookmarks-work (:color blue)
"work bookmarks"
("b" (mu4e-search "banana AND maildir:/work") "banana")
("u" (mu4e-search "flag:unread AND maildir:/work") "unread"))
(defhydra my-mu4e-bookmarks-personal (:color blue)
"personal bookmarks"
("c" (mu4e-search "capybara AND maildir:/personal") "capybara")
("u" (mu4e-search "flag:unread AND maildir:/personal") "unread"))
(defhydra my-mu4e-bookmarks (:color blue)
"mu4e bookmarks"
("p" (my-mu4e-bookmarks-personal/body) "Personal")
("w" (my-mu4e-bookmarks-work/body) "Work"))
Now, you can bind a convenient key to my-mu4e-bookmarks/body.