555 is still in beta, so I wouldn’t be surprised if something doesn’t work. That said, I haven’t experienced what you have (on GTX 1070 TI), though using 555 causes lots of kernel errors for me. Checking dmeg might reveal something in your case as well.
You can start steam just fine without the packages. In fact, if you install without them, it’ll ask you to install them every time, but you can skip that and it’ll work, just 32bit games won’t launch
Edit: Looks like I’m partially wrong, as pointed out by a commenter below, steam currently only launches the 32-bit version of the client, despite support for a 5l64-bit client