A long time ago, I worked on Renderfarm.fi, which was like what you're proposing but free. I was just an extremely junior developer working on the front end. The volunteer computing system itself was based on BOINC. I recall it was quite the effort to keep it running. If I remember right we rendered everything multiple times on different nodes to make sure that jobs weren't being faked.

There's no point to this post other than a trip down memory lane. I wish you the best with this project!