tiff2dng is a simple utility to convert a TIFF file in 32-bit floating point linear light to a DNG file in 16-bit integer sRGB. Be aware, there is some information loss inherit to this transformation due to the conversion.
If anyone sees this and knows how to go from an sRGB TIFF to sRGB DNG do let me know; it seems like the LinearRaw tag for PhotometricInterpretation could possibly be replaced with RGB to accomplish this, but the resulting images did not appear correct.
Using a system with Nix, run nix develop. This will put you into a shell with the required packages. You may then run python tiff2dng.py --help to see the following:
Usage: tiff2dng.py [OPTIONS]
Convert a TIFF file in 32-bit floating point linear light to a DNG file in
16-bit integer sRGB.
Options:
--input TEXT Path to linear light 32-bit float TIFF file.
--output TEXT Path to output 16-bit int DNG file.
--help Show this message and exit.