I found a solution:

#+begin_src elisp
  (defun devicetree-ts-mode--node-address (node)
  "Return unit addresses for NODE concanated with @."
  (mapconcat (lambda (children)
               (if (string-equal (treesit-node-field-name children)
                                 "address")
                   (treesit-node-text children t)
                 ""))
             (treesit-node-children node)
             ""))

(defun devicetree-ts--mode--name-function (node)
  "Return name of NODE to use for in imenu."
  (let ((name (treesit-node-child-by-field-name node "name")))
    (concat (treesit-node-text name t)
            (devicetree-ts-mode--node-address node))))
#+end_src

-- 
Best regards,
Aleksandr Vityazev