Switch from provided router/modem to my own

I tried going through Tier 1 support to reach Tier 2 or Advanced Repair to see if the CPE MAC (or maybe a different provisioning profile?) could be released. I have my own device that I want to connect directly to the Nokia ONT (or ONU), but Tier 1 can’t escalate to Advanced Repair unless their system allows it based on the ticket. I left the device offline for 30 minutes with no luck. I also tried cloning the MAC of the XB7 gateway—both the ONU and my device recognized each other, and the WAN was set up for DHCP—but it still didn’t work, likely due to further restrictions (CPE or provisioning profile). At this point, the only option I see is switching to another provider in my building (unless someone has advice here).