I have platformIO installed under VSC, however when I open a project, usually using the pioarduino platform, it asks me if I want to install the pioarduino extension to VSC. So, my question is “should I install both extensions?”

I can build projects with the PIOArduino platform with the regular PlatformIO core and PlatformIO VSCode extension just fine. I don’t think its required, it just gives you a different set of features. You should definitely not install both at the same time.