You could also look at what Alberto did for ART. I haven’t have time to try and automate it…he added external mask to ART and then wrote a little app to use segment anything.
It produces a png I think and not a pfm. I walked through it manually and converted the png to a pfm and then used the DT external raster mask and it worked pretty well for a sky, water and some other small tests.
My thoughts for DT, were if it could be used like the external editor in that you could call the mask app make the mask from the selected image and then have it roundtrip and add the copy back to DT then it could be used as an external raster mask… we would just have to do a conversion step as it exists now or code it more cleverly to do the png to pfm…