https://www.jstage.jst.go.jp/article/jplantres1887/84/996/84_996_377/_pdf
Some work done in Japan shows its possible to obtain hybrids across different sections of the Ipomoea genus.
A list of Ipmoea species with tubers, with edible ones in bold. From https://ora.ox.ac.uk/objects/uuid:b6180742-7ee0-4dfa-844c-94bccfe0a0fc/files/m4ba41d80e15a2eb63e5a499da2cbdb0f
Oh, cool, Ipomoea leptophylla is on the list! That's one I'd really like to see crossed into sweet potatoes, to see what would result. Ipomoea leptophylla is supposed to be super drought tolerant, and the roots are edible (though by most accounts, apparently not very tasty).