These are fair questions I was not aware we link here from MetaPDF.
We introduced it as our working title of the project here in the forum with the an early beta and the name stuck for some reason. The confusion is clearly our fault. Still, the situation is as follows: Paperpile has a PDF viewer which is currently in beta and which will be updated soon and hopefully go out of beta also in not too distant future. We support this as a part of Paperpile.
The future of the MetaPDF beta service will be decided in 2018. It will be definitely be a commercial product for developers but the future of the consumer version is still unclear.