What makes real kernels take man years to complete is the hardware support, the majority of Linux source code is drivers - the endless tables of hardware register definitions, opcodes and state machine handling.
I have zero knowledge about this area though
Drivers exist to ultimately turn actual hardware circuits off and on, often for highly specialized and performance-critical applications, and are often written based on the requirements of a circuit diagram. So any unified driver platform would also involved unified hardware standards, likely to the detriment of performance in some applications, and good luck telling Electrical Engineers around the world to design circuits to a certain standard so the kernel developers can have it easier.
That's like asking the alchemist to publicly publish their manuscripts.
In an ideal world, yes. However, we don't live there. Until a few years ago, GPUs and other drivers were guarded more carefully than the fucking Fort Knox.
Once you publish your drivers, you reveal a part of the inner workings of your hardware, and that's a no-no for companies.
Plus, what the other commenter said - getting hardware guys to design for a common driver interface is probably not gonna get traction.
If you mean, in general, for the hardware that already exists, that's what the HAL (Hardware Abstraction Layer) of the operating system tries to do.
If you mean standard logical interfaces, those exist. Also, hardware interfaces are highly standardized.
The problem is that the drivers are exactly the code you write to make all the abstractions fit each other. So there is very little you can do to abstract them away.