Ultrasonic sewing machines have been around for decades. They are very limited in the fabrics they can work with and are mostly used for industrial textile prod

Ultrasonic sewing machines have been around for decades. They are very limited in the fabrics they can work with and are mostly used for industrial textile products, disposable items, and for things that need to be waterproof, like dry bags. Gluing is used a lot for things like interfacing (stiffening collars) and hemming. You need a fairly large seam area to get good adhesion. Since the glue makes the fabric stiffer this would make the seam uncomfortable.