I am using GNU Linux, Manjaro distribution ... so lets say I boot inside Manjaro and login to KDE Plasma Desktop environment... and now run GaryOS inside my cur

I am using GNU Linux, Manjaro distribution ... so lets say I boot inside Manjaro and login to KDE Plasma Desktop environment... and now run GaryOS inside my current OS and can install Gentoo from current OS. Can I do that, so its like install Gentoo from another OS ? Please can someone explain. Thx.