It should be noted that multijunction cells here are not a 1:1 comparison and they are made by effectively stacking multiple cells that have different bandgaps to absorb more of the light. The limit for single junction is ~33%. One of the big potential applications of perovskite is depositing them over current silicon cells to form a tandem cell.

I don't see how a raspberry pi helps the goal at all, can you elaborate? I'm thinking if you were to try to do a ghetto API you could use Puppeteer or an equivalent which could run on an pi I guess, but also basically any computer. I would just run Puppeteer on whatever hardware you are using for the rest of your app, be it your PC, AWS...