Yes, a new version of AutoControl, compatible with MV3, is being developed, but it's uncertain when it will be completed as it requires a complete re-engineering of the source code.
Regarding non-windows support, the situation is not auspicious. A few years ago there was an attempt to port the native component to other OSs (Linux and Mac). Unfortunately, we discovered that those OSs lack the necessary mechanisms (system calls) to implement AutoControl's functionality with ease. Due to this, the implementation cost would be significantly higher.
Given those challenges and the modest popularity of the extension, we decided to put that effort on hold.