On top of the mechanical issues, CRT glass also functions as x-ray shielding, for which reason it is leaded (Pb). You can't really make that part lighter.
According to [0], about 1.2 kg (2.6 lbs). Surprisingly this is mostly in the neck and funnel of the tube - the screen itself uses different metals because lead would affect its optical performance.
https://en.wikipedia.org/wiki/Cathode-ray_tube#Body
https://www.epa.gov/hw/frequent-questions-about-regulation-u...
(This isn't really an answer to the overall question—just a narrow observation of interest).