Atomos announced today that it will support RAW output with some Olympus cameras in the future. The OM-D E-M1X and Olympus OM-D E-M1 Mark III mirrorless cameras are expected to enable RAW recording via HDMI with the Atomos Ninja V starting in winter 2020. These will be stored in ProRes RAW format developed by Atomos and Apple.
Olympus cameras are not very popular in the filmmaking community, although as MFT cameras they offer some interesting features (e.g. 5-axis image stabilization). However, Olympus announced three months ago that they are divesting their camera division - with still unforeseeable consequences for further camera development.
Also Atomos/Olympus have not yet announced any further details in which formats the camera will output the RAW signal. Sigmas fp or the mirrorless Nikon models Z6/Z7 combine single sensors before RAW output, which makes RAW recording absurd.
Since the update is still at least three months away, current Olympus users can be curious about what they will be offered here. However, it can be assumed that the update will be available free of charge - as with all other camera manufacturer combinations so far.