I have recently published a substantial entry (some 30 pages) on Pope Michael which forms part of the important World Religions and Spirituality Project (WRSP), an online resource focused on new and emergent religious groups, edited by Professor David G. Bromley at Virginia Commonwealth University.

David Bawden (1959–2022) was elected Pope Michael I in a 1990 conclave in Kansas.  He was neither the first nor the last man to become an alternative pope during the twentieth century. There have been dozens of others who claimed that they, not the vastly more recognized pope in Rome, are the true leader of the Catholic Church. Generally, they argue that we live in an era of general apostasy and that the modern church, particularly after the Second Vatican Council (1962–1965), has nothing to do with true Catholicism. Several of the latest Roman pontiffs were antipopes and leaders of a new non-Catholic religion. Most alternative popes assert that they were elected through direct heavenly intervention, and David Bawden was the first elected in an alternative conclave. He claimed the pontificate for thirty-two years, leading a small group of followers.

My text is found here