Compressed RAF (Fujifilm, 24MP) ~20 MB
DNG (24MP) ~90 MB
It cost about 4 times more to store RAW files in DNG format.
 replies(3): 
DNG (24MP) ~90 MB
It cost about 4 times more to store RAW files in DNG format.
Coincidentally, most proprietary RAW formats are just bastardized TIFFs, and DNG is also a TIFF derivative...
There is zero technical reason not to use DNG. Leica and Pentax use it just fine.
(See: ActivityPub)
Of course that even Adobe DNG converter can do what the GP asked for (I just tried it[1]), not that I would recommend it for Fuji files. And not that it matters anyway, since the whole point is producing DNG files directly, not converting them.
Edit: on my Fuji X-T5 files, using mosaiced data with lossless JPEG-XL compression (supported by MacOS 14+, iOS 17+, and the latest Lightroom/ACR):
    edengate:1$ ls -l
    total 163664
    -rwx------@ 1 aram  staff  40894672 Apr  4 15:25 DSCF1483.RAF
    -rw-r--r--@ 1 aram  staff  42894224 Apr  7 16:51 DSCF1483.dng