At least on Android the browser itself can lack the rights to listdir and only gets access to file you picked via the system picker, rather than the browser having unlimited access and only delegating only some of that access to the Web app.
Well some other comment mentioned audio/video and those are seemingly aways different
Which is probably fine for your users. In every browser it plays video and has basic controls like a start/pause button, a timeline and a volume control. While the video is playing they even look identical: it's the video, playing; with controls only visible on hover.
The differences aren't an issue for the actual user, they are an issue for the designer that tries to have the website look and feel the same everywhere. Preferably look the same as it does on their MacBook.
> <audio controls src="example.mp3"></audio>
> <video controls src="example.mp4"></video>
Which look different in every single browser and can't be styled without JavaScript. Wish these were implemented better.
And an unfortunate number of recreated controls seem to have the serious UX sins.
"looks different in every single browser" is a minor issue. Might be nice if they were restylable via CSS, though.
File pickers:
Color pickers: Date/time pickers: Numeric sliders: Suggested options for text fields: Summaries with expandable details: Media players with controls: