3D sports stadium model for artistic Augmented Reality project: clean up, coloring, poly reduction, export to .glb

I have a finished 3D SketchUp model of a sports stadium (9MB). - Poly count is 77.270 - Material count is 90 - Noteworthy: the stadium has a special, repetitive façade. I need the following: 1. clean up – remove elements from the model to strip it to facade, pitch, and the inner architecture; remove one scene (there are two, but no animations); move model to [0,0,0]; reduce distance from origin to =0. 2. color the stadium' façade with a rainbow color scheme as if it is "lit up" that way. 3. reach the following specs for the .glb file format that i require as a final outcome, through e.g. poly reduction, triangulation, texture compression or other render pipeline trickery: - set pivot point to base of the model. - set forward vector of object along Z axis. - reduce .glb poly count to a max. of 35k tris, with acceptable (recognizable) looks, but less polygons would be preferred. - max. .glb file size = 10MB but way less would be preferred, e.g. 5MB. 4. export the optimized model to .glb so that I can test versions of it in an Augmented Reality environment for performance, orientation and aesthetics. Might involve two, three rounds of back and forth to get it right. Will be used for a non-commercial, media artistic project.