Open a file with su/sudo inside Emacs

Question

Suppose I want to open a file in an existing Emacs session using su or sudo, without dropping down to a shell and doing sudoedit or

Answer 1

Tramp does not round-trip sudo via SSH, it uses a subshell. See the manual: https://www.gnu.org/software/tramp/#Inline-methods

Therefore, I recommend that you stick with TRAMP.