Installing MSYS2 to run a bash script is like deploying an A-10 Warthog to light the fuse for one of those fountain fireworks.
There are much better ways to install things in windows. Such as MSI files if you need to change paths and registry entries. Chocolatey if you want a 'aptget' like usage, there are several of these types. Using bash to install something is unique. I personally am a fan of in place portable install, unzip, run exe, done.
Anyone who doesn't already have a bash environment installed on Windows isn't the target of install.sh.