They offer both Ubuntu and pop! os; I don't think it's fair to ask for more distros. If you want Mint, just install Mint. An install of Ubuntu 20.04 for me required zero configuration on a new Oryx Pro 16" that I bought a few months ago.
It would have been nice (imho) if they offered Mint as an option as it would potentially save me the pain of hunting down the proper drivers and hoping I can figure out how to install them and get the workstation I want to actually work.