I don't use brew but I do use Guix on top of PopOS, for most of the same reasons I use Guix System as a daily driver distro on my other machines. The PopOS install is meant to act as a "Windows replacement" so it has proprietary drivers, Steam, etc. For anything that's not a system package I get it from Guix if possible, because I prefer Guix's package management and its commitment to software freedom.
On Windows I use Scoop which has a handful of similarities in terms of user package management.
It absolutely is. WSL literally runs Linux in a virtual machine.