Anything that isn’t UL listed is not a “Safe” but rather a fireproof cabinet. Everything sold as a gun safe at a big box store is basically laughable junk. Names like “sentury”, “liberty”, stack-on” are all not safes, and shouldn’t be treated as such. They keep honest people out and can be defense in a small fire.
That being said, all most people need is just a slightly secure, slightly fireproof box as having possessions stolen or burned in a fire isn’t a huge probability so some of them could work for you. Just understand that they aren’t safes.
now since you didn’t mention firearms I’d assume you were looking for something to store important papers and jewelry and such. If you are planning to get a smaller “safe” for that stuff be sure to bolt it down or secure it with a cable to something large (bed frame or something similar) as what you are really doing is concentrating everything valuable that you own and making a convenient carrying case for a would be thief to worry about opening later. Also, a safe should be treated as the last line of defense, so picking a good location away from water or fire hazards and not obvious to a thief would be better protection than the safe itself.