It was my main concern, so I dualboot (my main drive 500gb SSD runs Fedora while I have another SSD of 1TB with Windows 10).
Most games I play are running flawless on fedora (rn I'm playing No Mans Sky), as most Steam Games (you can check protondb for your favorite titles) and I've been more than a month without booting windows, but other titles as Fortnite can't run on Linux.
For your games on Epic and GOG you can use Heroic Launcher. Gaming on Linux is getting easier on daily basis.
Also, you can always try Linux first in a Virtual Machine (for example VirtualBox) to get a feeling of it without altering your hard drives, I started that way!
Regarding spreadsheets, I use LibreOffice Calc. Is not as feature rich as Excel but for me it gets the job done. I'm not sure if it works, but maybe you can set up a Windows Virtual Machine in Linux to use excel in it.
Two things are preventing me from switching to Linux