Responded to @fabionatali:
@fabionatali Have you considered getting an SFP ONT modem and plugging that directly into a router like Mikrotik RB5009? I have success with this module https://hack-gpon.org/ont-odi-realtek-dfp-34x-2c2/ and following this guide https://www.hitoha.moe/odi-dfp-34x-2c2-gpon-onu-sfp/