Is an orphan obligated to honor parents?
This d'var torah makes the argument that an orphan can still fulfill the obligation to honor parents, because the sages interpret it more broadly than just your two biological parents. (See the link for a good explanation of the reasoning.)
If one without living biological parents can still fulfill this obligation through teachers, then does this imply a lifelong obligation to have either parents or a teacher to honor? The eilu d'varim passage in the Shacharit service lists kibud av v'eim as one of the obligations without measure; I had thought that meant while you have parents and maybe after to honor their memories, but the linked interpretation implies something more active and ongoing.
I am aware that we are obligated to keep learning (and talmud torah is part of that eilu d'varim passage too), but one can learn in many ways. One might study books, or have a study partner who is more of a peer and less of a teacher, for example. And I'm aware of the passage in Pirke Avot to "make for yourself a teacher" -- good advice, but as far as I know Pirke Avot is not a halachic source.
Is an orphan halachically obligated to have, and honor, a specific teacher in place of parents?