Pretty sure it was supposed to come in a dot upgrade of Xcode 13 (and the very basic create part was in a beta if I remember correctly). As there's also no sign of it in Xcode 14 betas it would seem like it has most likely been abandoned, which is kind of sad

Don't know if it's any help in your case but notice that you can insert a filter at the linear stage via the kCIInputLinearSpaceFilter option

Let me add that we have run into exactly the same situation with a number of compute shaders that use read/write textures where it seems to work just fine on hardware where in fact it is not officially supported (both Mac and iOS devices). Can only guess that it will depend on the exact code whether it actually works or not

In case you are not already aware of this - Notarization requirements were temporarily loosened so that it would succeed in spite of warnings. This is no longer the case