Sadly, the ecosystem of sta*ckexchange network is infamous for being unfriendly towards some segment of people and I apologize for all of us. Now, of course there's always a possibility that trial & error like this could break your system, but if you still want some input, Steam will usually need i386 and amd64 architecture to be installed. Do you have them installed ?
sudo dpkg --add-architecture i386
sudo dpkg --add-architecture amd64
sudo dpkg --configure -a
sudo apt-get update && sudo apt-get upgrade
These are packages that Steam usually need to install :
Steam needs to install these additional packages:
libc6:amd64 libc6:i386 libegl1:amd64 libegl1:i386 libgbm1:amd64 libgbm1:i386 libgl1-mesa-dri:amd64 libgl1-mesa-dri:i386 libgl1:amd64 libgl1:i386 steam-libs-i386:i386
My advice is, to be safe just check one-by-one if each of them is installed using
sudo apt-get install [package_name]
If the package is installed, you'll get information. If no, the system will install it for you by hitting "Y". for example
sudo apt-get install libc6:amd64
sudo apt-get install libc6:i386
And so on for each package, if the system ask you to uninstall other things (especially "bunch" of other things, then hit "N" right away). At some point, you'll find out which ones are "not installable". Take notes for these packages and investigate using "aptitude". For example, a problematic one is "libegl1:i386", use
sudo aptitude install libegl1:i386
"aptitude" command will give you options of what available choices we can do to install this package, usually including downgrading other packages (image attached). "aptitude" can be very useful, but also please be careful to use it. I can't exactly give more input on what option number you should choose, because it will be different for each system. This is something that only trial & error can do.
Make sure all the packages that originally can't be installed are now all installed, do reboot (just to be safe), then try to install Steam again.
