After scouring the forums, I learned that by default, the ONT outputs a coaxial signal, not ethernet, meaning that unless I use their router and/or TV package, I cannot receive internet. I plugged it in to the ethernet port to find that it was not receiving internet. If you are asking about the modem, you can buy your own as long as as it is compatible with Verizon Fios, and they may offer a self-service way to register your. This morning, I tried setting up the router. I politely declined, thanked her for her time, and hung up. She then tried to sell me a $40 TV package. The service representative confirmed that since the ONT is already here, all I need to do is plug my router in to any ethernet port in my unit after midnight (I specifically asked what time). Last night I called to make sure I had everything I needed and was not waiting for additional equipment. The activation date of my service is today, January 22nd. Because of this, I was able to elect to self-install and use my own router.
I recently moved to an apartment with a pre-existing fios ONT installed (but no leftover fios router) and chose an internet-only package. Wi-Fi extender provided during or after installation if recommended after Wi-Fi performance analysis by Fios Tech or upon customer request.