How can you say a catalog is limited when you get 4 hours of new music a day?? It’s a good way of thinking of it.

I was referring to the limited amount of artists, no big names as of yet – but that does not bother me. I like listening to new and lesser known artists. There is so much good music out there!

But I see it looks like you pay as you stream up to $11.20

It is not a hard cap at $11.20, it is just one example of how much you would spend in a month listening to new music for 4 hours a day. Their model is based on gradually increasing the price every time you stream a song. First stream of a song costs you (less than?) 1 cent. The sixth time you listen to a song, you would have paid about 10 cents and by the ninth listen you have paid for it in full (about a dollar in total) and you will not have to pay any more to listen to it, as you now own it.

In other words; exploring new music is quite cheap, and when you find a track, artist or album that you really like, you will pay a fair price and own it after the ninth listen. And if you do not stream for a while, you're paying nothing, as there is no monthly fee. I have to say I really like this pricing model!

It doesn’t appear to be FOSS

Yes it is, but I will add a proposal where I suggest that this is mention on their landing page, or at least have a link to the repo in the footer.

Btw, it is a great feeling to be a member of such a project, not just a "user" like with Spotify. As a listener and member, I have voting rights and can also influence the development of this project.