It’s mentioned in the bottom left. Whoever made this has a problem with their ownership having been Russian in the past.

Plug for Medito, which is a free non-profit for guided meditations. Not sure if the apps are open-source but still, they’re a good organization in stark contrast to the many other meditation companies that are very much for-profit.

So what’s the main advantage of this over F-Droid? Theoretically more secure?

I love the idea! If there was good support from something like GrapheneOS or /e/OS I would be looking at one of these.