I seem to recall very Android phone I've had came with an app called "Files". If not named "Files", they always had some kind of baked-in file browser. The last few phones have been Pixels, I don't remember exactly the specifics of the one on the Motorola devices I had prior, but on the Pixel devices its this app:

https://play.google.com/store/apps/details?id=com.google.and...

No ads. Sure, it tries to group things by categories and searching at the very top, but its still easy to see "Storage devices" which lets me navigate the actual folder structure. My Pixels have come with USB-C male to USB-A female adapters which allow me to plug in things like flash drives, memory card readers, cameras, external hard drives, even other Android devices and access the files through the Files app.

Generally you can exchange some amount of money in return for not seeing ads...