"what's the advantage of using GNU/Linux distro over a distro like
fedora/redhat?"
Fedora and Redhat are GNU/Linux distro's many people in the free software
community chose to call what most people call "Linux" "GNU/Linux" the reason
for this is explained here:
https://en.wikipedia.org/wiki/GNU/Linux_naming_controversy and here:
https://www.gnu.org/gnu/why-gnu-linux.en.html
The advantage of Trisquel over Fedora is it includes exclusively free
software so you have full control over your operating system and can know
everything that your OS is doing.
Some of the advantages of free software are explained here:
https://www.gnu.org/philosophy/shouldbefree.en.html
"would I be able to use alternative drivers to nvidia drivers so that I still
can play games under Linux via steam or wine?"
You would be able to but as you would most likely be running non-free
software it defeats the point of running Trisquel somewhat.
