Okay, I have an update.
It turns out that you CAN disable MOST of the Apple Intelligence features without compromising HomePod features or CarPlay by either:
A) Downloading and installing the profile I just created that does everything that follows below here (https://github.com/carlosonunez/bash-dotfiles/blob/main/ios-...), or
B) Doing these things:
1) Going to Settings > Siri and changing the "Language" to something other than "English (United States)." (I changed mine to "English (Canada).") This automatically disables Siri AI and restores Siri Classic. You'll need to go through voice training again though.
2) Going to Settings > Screen Time > Content & Privacy Restrictions > Siri and setting "Siri" to "Siri Classic."
3) Going to Settings > Screen Time > Content & Privacy Restrictions > Siri and setting all Apple Intelligence features (Writing/Math Assistance, Image Creation, Extensions) to "Blocked" or "Don't Allow"
4) Going to Settings > Messages and setting "Summarize Messages" to OFF
5) Going to Settings > Mail and setting "Summarize Messages" to OFF. (This might disappear after following step [3])
Steps 1 and 2 delete the Apple Intelligence models from your phone, giving you about 30GB of space back.
(Courtesy goes to this Reddit post: https://old.reddit.com/r/ios/comments/1wh7i10/ios_27_how_to_...)