Graphic Card Upgrade - for a Mac Pro 2012

I've read thru this guide which is amazing but I didn't see recommendations for graphics cards for my Mac Pro 2012 5,1. I'm currently running High Sierra 10.13.6 which is the highest OS my Mac can use with the stock graphics card. I'm not a graphics designer and don't do any heavy lifting, I just want a card that will allow me to upgrade to higher OS's and have the Apple opening screen which I gather some do and some don't. Also does anyone know if you change your graphics card can you upgrade beyond Mojave? UP to Catalina and Big Sur?

So first I'd love to get some graphic card make/model and then an answer about how far can you upgrade (OS) after upgrading to a metal card? Thanks so much

Thank you. This is excellent!