I don’t understand color profile much so I can’t give you explanation. But as I experimented for my dt-nind-denoise workflow, I don’t need to specify --icc-type when exporting to TIFF from darktable-cli. It’s more important to set the input color profile of the TIFF file when re-imported back in.
TIFF 16-bit should work fine for most cases, but I found data from highlight reconstruction is only retained when exported as TIFF 32-bit. For my workflow, the TIFF files are only temporary and would be deleted later, so setting them to huge-filesize TIFF32 almost has no downside for me while ensuring no data is loss.
I’ve also experimented with OpenEXR but gave up shortly, mostly because there’s no Python library that supports OpenEXR extensively (it even throws a warning about a current security issue in OpenEXR format). Besides, EXIF is not embedded in OpenEXR so you’ll lose all the needed info about the shot.