Still an hybrid kernel like the Windows NT one is a newer approach than the old monolithic Linux (a unix-like 70's one clone) with modules... The fact it's stable and relatively faster in some occasions has other reasons
Imo no, a simple web engine is a totally different thing from a kernel project I don't see a way they could possibly do that, it's too much used currently for different things unlike a plain web engine...
This is just what WSL 2 is, before they were using a sort of reverse Wine (which only took less years compared to the Wine, a community project, since 20 years I think? And it's still not complete) and now they are using another approach based on the same userspace but with the actual binaries running on a Linux kernel inside a small VM, which could possibly be a great approach... But I don't know how they can gain access to physical devices without being passed to Windows, we should see how they are going to manage it.
Anyway, the hardware acceleration is not really an issue, the fact is there are not any X.org servers with hardware acceleration (Xming is not perfect) currently existing in Windows, as for wayland that's another story...
As for audio, one can easily run a pulseaudio server on Windows...No matter if they run inside a vm or not
It really depends on how it's built, considering it only needs to support a vm theoretically, it can be even less than 1M... Not considering userspace, obviously
But remember Linux kernels on distributions have all sort of drivers on it, and the kernel + initramfs + modules can weight up to 1gigabytes, I don't think the WSL 2 approach needs all those drivers or an initramfs. The Linux Kernel on android for example I remember being much smaller than the one present on GNU/Linux distributions
If one builds the linux kernel with all the modules inside the kernel image (builtin options in menuconfig), this is going to weight like the modules folder you got in /lib/
I don't honestly think they care about linux market share at all rather than simplifying life for developers... Or changing the uses for Linux in servers or ioT
Don't start another flame war please ç_ç