It's insane to me that there is this object a few meters away from me and to access its data it needs to be sent to the Internet and back crossing multiple API's just to show a line graph that goes up and down.

That's correct. In my case it sends the data to the company's server and I access it on a smartphone app made by a third party, when this could all be accessible over LAN only, or, better yet: just make it a physical LED panel on the inverter.

My solar panel connects to the Internet so it can tell the servers when the Sun is out.