This is a very simple question, but I'm not sure how to query the installed packages and their versions in MSYS2. I have read the MSYS2 wiki here and the Arch Linux wiki here, but they do not seem to mention it or I missed it. Any help is appreciated!
Edit: It appears the wikis do cover this as mentioned by the answer.
Since msys2 is based on pacman, you can use typical pacman commands.
For example, in this case use pacman -Q to list installed packages (many additional flags to customize the search are available).
Further reading: