Looking for feedback (and potential sponsors) for an app that pays users to put their phone down

I'm thinking about building a focus app with a slightly different business model and wanted to see what you guys think about it.

The idea is that companies sponsor people's focus sessions.

A user starts, a 50-minute focus session then one productivity app or company sponsors that session. If the user completes it, they earn a small amount of money funded by the sponsor.

So instead of showing users a bunch of ads, it would be more like: focus for 50 minutes and it would say sponsored by Your App and then the user earns money, and you earn impressions or clicks or customers who are actually interested in the app you built.

I was thinking the first sponsors could actually be other indie productivity apps, because someone who downloads a focus app will download it to be more productive.

Maybe 10 productivity apps put in €50 each. Each sponsor gets a certain number of completed sessions with their app shown as the exclusive sponsor.

The interesting part for sponsors is that the audience would obviously be people who are already interested in productivity/focus tools.

I'm still validating this before building it.

If you build a productivity app, would you put €25–€50 into something like this to test it?

And if not, what would need to be different for you to consider it?