for developing in camera you have a new output fileformat:
‘Raw-to-TIFF output
In addition to its Raw or JPEG options, the X-T4 gains the ability to output 8 or 16-bit TIFF files via its in-camera Raw conversion interface. These are images demosaiced by the camera but saved as large, minimally compressed 16-bit files, rather than lossy 8-bit compressed JPEGs. This would give more files that are more malleable than JPEG output, but less manipulable than Raws. A 16-bit TIFF is around three times the size of a Raw file. The TIFFs are created from the camera’s 14-bit Raw data, which makes sense, give the marginal gain of running the sensor in 16-bit mode (there’s a barely measurable difference between 14 and 16-bit output on the Fujifilm GFX 100, which uses the same pixel design). But if you want high-quality, ready-to-edit files that correctly reflect the camera’s Film Simulation modes and detail reproduction, rather than trusting of a third-party Raw converter, it gives you options.’
I don’t see the point of in-camera conversion: Why not provide a software to convert raws to such tiffs and save the SD-card space, use less battery, probably can do/save more shots per second, …?
Fujifilm provides an intermediate solution: Fujifilm X Raw Studio uses the camera engine to develop the raw files (https://fujifilm-x.com/software/x-raw-studio/). Apparently it’s interesting for people who like Fujifilm’s color and tone science, and provides a nice speed up for the batch processing of many files.
Unfortunately, since it relies on the camera’s processor, the output file format is dependent on the camera: for an X-T2 you can only convert to JPEG format, but probably for the X-T4 the software will allow you to convert TIFF.
This way, hopefully an X-T4 owner would be able to shoot compressed raws, transfer the files on your computer, and batch convert them to 16-bit TIFF.
Also, you can choose to batch convert the raws using a conversion setting or a film simulation that preserves as much of the shadows and highlights as possible to prevent clipping, and later on tweak the look from you favorite image processing software.