Can I make my phone start recording sound without removing it from my pocket? Sometimes I would like to record sound from my Android phone, very quickly, without having to touch the screen.
(Example: record funny situations in the street, funny sounds, etc. )

Can we launch sound recording "with hands in the pocket"? (i.e. without using the screen)

More generally, is it possible to launch an app with hands in the pocket, by pressing one of the buttons during 3 or 4 seconds for example?
The only hardware buttons that can be used by apps (to launch other apps or start a recording) are the “camera” button on the device and the “media” button(s) on the headset. You’ll need a sound recording app that support it, or use an automation app like Automate with its Media button and Audio record blocks.