Play radio offline?

I've been trying to search for offline radio apps for my Samsung Galaxy. I tried all of these - https://freeappsforme.com/best-fm-radio-apps-without-wifi/#Radio_Fm_Without_Internet . And they all require mobile data to be turned on - but then why is it that most mobile phones, including mine, have Radio built in? The only problem with my built-in Samsung Radio is that it needs the earphones to work. I've tried through the loudspeaker, but they all need mobile data. Are there any radio apps that work offline?