We love these interlocking wood tiles! Can be purchased at Home Depot, Amazon & Ikea
https://tinyurl.com/ya8aky7a

I use an inexpensive tarp.

Hey dude!

I have a patio (deck) also and i didnt put anything ins besides the patio floor itself! I just wash it like once a week due to traffic and sweat. I wouldn’t worry about fumes from the stains etc on the floor since the floor stays very cool. Regardless of the flooring you do you will eventually have to wash it in my opinion! Hope this helps! Cheers!!

Andy.