My devices just sit on a desk lol. I have two laptops working as servers in another room. But if you wanted to be safer from a potential fire, a metal cabinet

My devices just sit on a desk lol. I have two laptops working as servers in another room. But if you wanted to be safer from a potential fire, a metal cabinet is the simplest way to do it. A deflagration from a lithium battery would just heat it up a bit, maybe start burning other stuff inside, but it's highly unlikely to spread beyond that as it would fizzle out due to lack of fuel (also temperature).