Would be cool to be able to (with stuff like a SubDFaceEdgeVertexToggle ish) be able to do bigger selections, make them UV seams, then maybe manually going in and removing a few. (instead of the reverse).
So outside of the uv editor/unwrap, so potentially an additive and a variant that removes the seams.
edit:
hmm assuming that doing any edits always destroys the seams, having this command would then make a custom plugin viable which would save seams manually/some other extension way, then just call that ‘SelectionToUVSeams’ command to send the data over to the unwrap or something like that.