Emissive use same HDR values than rest of pipeline. It’s just matter of balancing emissive vs directional light intensity. 1.0 isn’t any meaningful value.
You could try this. Set all normals to use world space(instead of tangent space). Just make it point let say upwards. Then add directional light with 0.0 as indirect light intesity. Setup all materials specular 0.0 and roughness to 1.0. Plug albedo color to emissive with some multiplier to get right amount of shadow color.