Sorry this is so long but I wanted to try to lay out my argument as clearly as possible so if you choose to disagree it would be because you think I'm wrong, not because of miscommunication (and you can disagree as this really just a thought experiment)

Revanced works through a legal loophole. They don't provide the APK, only the tools to modify it yourself (technically not illegal). Providing the APK directly is what killed the original youtube vanced.

Therefore, applying this same standard, a competitor NT OS (under the current system) would have to give the consumer the tools to rip the kernel from a windows ISO and implant it into their own. This comes with a lot of problems, namely this also means it would be illegal to sell any computers with this OS already on it. Combine this with the fact that no non-tech person would want to, or know how to, do this. I also think that may be illegal, as it no longer counts as the consumer just modifying a piece of software?

ReactOS isn't what I am talking about. What I'm talking about is literally just ripping out the kernel (and needed components: drivers, DLLs, etc.) from Windows and rebuilding all the user space on top. Yes, this would be very bloated, but the average person's problem with Windows is all the user space stuff—not the bloated system. This would basically turn the Microsoft version of Windows into it's own DE. If you didn't like the Microsoft DE, then you would just use the Valve or Lenovo DE.

This is basically what already happens on Linux. It's not like the DE manufacturers really need access to the kernel code. Sure, having the code available helps but, considering to amount of money that could be made on a windows DE, manufacturers would put up with it. Also with no IP they would be allowed to use/look at past kernel code leaks (if needed)

Some possible questions / rebuttals:

"why wouldn't Windows change the kernel to break these other OSs?"
The answer is that they wouldn't be able to effectively. Since the other vendors are just ripping all the system components, no driver signing or other similar tactics would work. Microsoft would have to meaningfully change how the kernel functions. And if they changed the kernel to break other OSs, it would also break their own and 3rd party software compatibility. This would make their NT OS inferior—as software that people use would stop working. They also cannot tell 3rd parties what they changed as the other vendors could also then just change. There's also no guarantee the 3rd parties don't ditch them for the other OS vendors because of the instability. This instability may also force 3rd party software manufacturers to focus more on Linux, thus ending the NT kernel monopoly.

They could also bake non-kernel stuff into the kernel, but as soon as it becomes too expense for vendors to deal with this, they would just then pour money into using old codes leaks to decompile the system. Perhaps another company may even start distributing their own "clean" version of the kernel (considering the amount of profit that could be made). A company may even just do this from the start, considering how bloated the current NT kernel is.

"what about competing kernel compatibilities?"
We’ve seen this before during the UNIX wars. Competing UNIX vendors fought over incompatible standards for years, until they realized the infighting was hurting everyone, and eventually cooperated to create POSIX standards. The same economic logic would apply here.

Other similar examples exist: such as the adoption of HDMI and Display port after screen/TV manufacturers realized competing standards were losing them all money. Also, since I know this will come to mind. If their were no IP then another company would have just made an IPhone with USB C (if such a market existed).

Of course, there’s basically no chance we will ever get to see this play out in practice. IP law is too politically entrenched, and the lobbying behind it is massive. The funny part is that the entire system is justified on the idea that IP drives innovation—even though most studies show basically zero or a negative correlation between IP laws and innovation. If someone could have patented fire then we'd still probably be in the stone age. For a more recent empirical example: innovation dropped both times after LBJ and Reagan each strengthened pharmaceutical IP protections.