Allow Setting Interpolation Method For Individual Smart Objects
There was a popular thread with this request that I guess was locked after UserVoice was converted to the forum? https://community.adobe.com/t5/photoshop-ecosystem-ideas/p-ability-to-choose-a-smart-object-s-interpolation-method-2013/idi-p/12249327
Anyway it's something that is pretty crazy that it hasn't been added in all this time.
I imagine it would be a dropdown that could appear at the top when the Move tool is enabled.
Here's the crazy thing: Nearest Neighbor scaling on smart objects is already possibly but only if you have it set as the Image Interpolation mode in the Preferences > General tab! So all that would need to be added for this feature is a dropdown setting and some kind of metadata property for the object on the backend to remember which interpolation method it was set to.
Because unfortunately even if you change the default to nearest neighbor temporarily to rescale a specific smart object then change it back, if you go to rescale that smart object again, it uses the new default.

