My goto for relaxing is "Lonely Mountains Downhill" for the Switch.
It's so relaxing, you can hear the nature and there's no background music.
It's a third-person biking game.
Interesting that you mention this! I like this game a lot, but would rather describe it as hectic and fast-paced (due to the many attempts to optimize race times or find shortcuts). But I do agree that the nature sounds and landscapes are lovely on their own.
