That is relatively convenient, DTAG is pretty open to provisioning third-party ONTs... However an ONT is essentially its own separate computer (the intel falcon platform actually runs a version of OpenWrt internally) which means that it will need some time to boot up, for some SFP-ONTs on turris omnias there is a report that after a cold boot the omnia will not recognize the ONT and that it takes a "warm" reboot before the OS sees the ONT...
Have a look at: