Anti-Phish wrote:VZ is not going to upgrade you to a GPON ONT unless you order a speed tier that requires it.
TL/DR: Focus on poor speeds and trying everything else but replacing the ONT and not BPON v. GPON.
OP might have better luck just claiming (accurately) that he isn't getting the promised speed, documenting the troubleshooting he did, and suggesting that the ONT is to blame, maybe not even mentioning GPON at all. I think Verizon will, after forcing you through a million troubleshooting steps, offer to replace your ONT. I'd suspect that they'd replace with a GPON unit since the extra cost of the unit is probably less than having to reinstall when and if a person decides to upgrade their speed and they are likely more reliable esp. if a user is complaining. Even if they replace with BPON, if it is able to give the right speed, OP should be happy, maybe it won't be quite as high over 75mbps as in his office.
Not to say that you can't mention GPON at all, but the more you focus on it and not the lack of promised speeds, the more resistance you'll face. I'd definately bring it up once they commit to replacing the ONT.