WSL1 is not Linux because it is mapping system calls from the Linux kernel ABI to NT. That sounds like what you're describing. WSL2 is a Microsoft distro running in a VM that integrates into Windows.
I use WSL2 every day and it has some annoying quirks with how their Wayland implementation behaves with DWM, but otherwise it's just a Linux environment.
WSL2 isn't exactly a distro. there's CBL-Mariner, which is a distro used for utility/plumbing, but it's pretty hidden internally. WSL2 is mostly:
1) a lightly-patched Linux kernel
2) a bunch of esoteric bridge stuff, namely:
2A) 9P for mounting the Windows filesystem on Linux and vice-versa,
2B) a Wayland server implemented via RDP(?!)
2C) Hyper-V NICs, dynamic memory and other VM integrations.
2D) even weirder esoterica like whatever magic lets CUDA work (and... directx? for reasons??)
but there's no canonical (pun intended) userspace. there are many Linux distros available; adapting a distro is usually pretty easy. for example, NixOS-WSL is lightweight and works quite well.
philosophically, WSL2 is a VM, but it's not an emulator, if that makes sense. there's a kind of convergence between OS and VM that's been going on for a decade and WSL2 has been riding that wave.
(disclaimer: I work for MS but not on Windows or WSL. I just think the arch is neat.)
I use WSL2 every day and it has some annoying quirks with how their Wayland implementation behaves with DWM, but otherwise it's just a Linux environment.