I'd argue the implementation detail is still hidden. You don't know if Applications use FUSE or are WASM containers or docker images or what not. Interface is

I'd argue the implementation detail is still hidden. You don't know if Applications use FUSE or are WASM containers or docker images or what not. Interface is a translator between what user understands ("I press button, channel changes") and implementation detail ("rubber dome changing resistivity, ...causing IR signal to be sent", ...).