I would very much like it if someone could explain how the sun could work on a flat earth

But the angles of those triangles would be quite differnet

Wait, where are these points exactly? Because I was imagining two points on the surface of the Earth some finite distance apart, with the third point being the sun

I understand what you're saying about the isosceles triangle, but there are a few problems. The most important of which is that the angle that you're measuring has to be with respect to the surface of the Earth on both models. On the flat model, the norm of the surface is always in one direction. In the globe model, the norm changes depending on where you are

I also wish I could use some pictures to explain, but I'm very new to discord, so I have no idea about any of that 😦

That's alright. We both understand that the earth is a sphere, so I trust us both to understand how triangles work