Xiaomi has released a camera accessory kit to accompany the Xiaomi 13 Ultra. To be available in at least China, the kit includes a protective case, a camera handle and a 67 mm adapter ring, among other accessories.https://www.notebookcheck.net/Xiaomi-13-Ultra-Official-camera-accessory-kit-turns-new-flagship-into-DSLR-lookalike.708362.0.html
Ah so that doubles as a remote shutter release, I was hoping for a secondary battery because that's half what grips are for anyway, but this works.