We haven't for a while, but we use to release iPhone-only and iPad-only apps. I think 2018 was the last time we released an iPad-specific app like that, and last updated that app in 2019.
The main thing that was needed was adding this to InfoAdditions, to limit it to just iPad:
Did you already have that in your XML under InfoAdditions?
I don't think we had to add iPhone screenshots for that app, can't remember if there was some way to skip it or if that requirement disappeared after we uploaded the IPA and it recognized it was iPad-only. Of course that was years ago, it could be that things have changed and App Store Connect doesn't expect you to try releasing single-platform apps anymore...