I think I can ssh into ONT, any command to manually ask the ONT to redo the PPPoE stuff and fetch the MAC?This info is available when you make the PPPoE connection. Some routers display it in the UI too.
Regarding the hardware upgrade, I've been getting IPv6 since more than a year. Not all areas in Kerala are upgraded, some are still on the legacy Ericsson (I think) hardware. Perhaps the pandemic has slowed the upgrades 🤷🏻♂️