Panasonic is working on a new box-style camera wiht an additional grip – check the recent patent JP2024-065694. The new camera looks similar to the existing LUMIX BGH1 (MFT mount) and LUMIX BS1H (full frame) models:
Announced: Panasonic 6K Lumix BS1H mirrorless full-frame box-style cinema camera (L-mount)
Via PhotoRumors