HI Jack,
That is right, Emision is a ‘flat’ Shader.
What you can do is model the texture of the glass and place an Emission behind it (sort of as it would be in real life).
If some light hits the surface, you ccould maybe get away with a Bump (Voronoi Texture, Minkowski Metric, zero Randomness) Node in the Normal of A Principled Bsdf and use the Principled’s Emission, but as soon as the light is in the dark, it’ll be completely flat. (I hope this still makes sense.)
