I think a nontrivial factor in Trump winning Orthodox Christians by landslide margins is Middle Eastern Christians resonating with GOP suspicion of Islam.
The Orthodox number was curious to me, because when I think of Orthodox Americans I think of Greeks, who might vote Republican on aggregate but certainly don't seem like an overwhelmingly Republican demographic (most of the Greek politicians who come to mind are Democrats). Your explanation makes sense in this regard.
Greeks are the largest ethnic bloc of Orthodox Christians in the United States, but their share is overall dwindling as they secularize and integrate. While anecdotal, I know a lot of Greek-American conservatives are angry at the Biden Administration for what they see as interfering with Church affairs. With more liberal Greeks increasingly going secular, I suspect they are mainly the ones staying in the pews.
Probably the worst Mormon total for the Republicans in 40+ years.
I suspect Mormons eventually end up where the Mainlines are. Their culture puts too much emphasis on being friendly and agreeable to really cohere well with the attitude of the Trump GOP. Their leadership also seems to be trending liberal from what I've heard as an outsider.