Like the sounds and sights of the natural world? check out https://www.calm.com/ There's also an app version you can download and carry with you.
Simple and pretty. The app has about 5 videos of nature, such as the ocean, or leaves in the rain, where a still camera sits much like a window to look out of onto the calm world of your choosing. There's also a longer collection of free soundtracks without videos (such as crickets chirping). The website has more videos than the app, and it can play in the background while you do things in other tabs.
These resources can be a great way to take a 5 minute breather before a stressful phone call, or provide a soothing background before sleep. If you are using it at night, stick with just the sound and skip the screen. Computers and phones give off a blue-tinged light that wakes your body up, no matter what's happening on the screen.
If you want to be more active with it, the app has meditation timers and trackers too. There features are more robust with a subscription, and then you get access to a variety of guided meditations. I didn't subscribe so I can't tell you about those. I'd love to hear your thoughts if you are using that service.
Recordings are no replacement for actual nature! A 5 minute walk can work wonders for your day and, on a regular basis, for overall mental health. But the best resources are the ones you'll really use. So consider this an additional way of finding a moment's peace and focusing, (or gently un-focusing) the mind, not a substitute for what's outside your door.