tl;dr - get a quantum setup if you can and an Ethernet extender, if you can't get quantum read on:
Ok, so in a "former life" I worked for Verizon before FiOS had a name. Back then we only had only two test beds, and were still calling it FTTP in press releases. (Fiber-to-the-Premises).
The data signal for the non-quantum STB's can be integral (when all data is run on the ONT's coax connection, often called the MoCA port) or injected (when the customer's data is run via ethernet, the MoCA port on the Verizon provided router, not the ONT, injects the data signal for the non-quantum STB's.) Quantum adds a new wrinkle, as the quantum client STB's can run via Ethernet only.
If you qualify for quantum, forget the older STB's and get an Ethernet extender and run an arris 1100-acp in the garage, you'll only need a powerful Ethernet signal. Any of the commercially available CAT5e or CAT6 amps (Ethernet extenders) will work for this.
If you can't get quantum at your location, there is another solution. However, current generation RF amps won't cut it.
If you choose to be an "injected" install (Ethernet for data) you can locate the verizon provided router (with MoCA bridge) in such a way that it splits the 400' distance. Since the router is now injecting the MoCA data stream onto the coax, the distance from the ONT becomes irrelevant. If poor wifi performance is a concern, just disable the WiFi on the Verizon provided router and use a different, high power access point.
A NIM (network interface module) was what we used for the first two years or so of FTTP/FiOS TV, before MoCA bridges were available integrated into routers. Once MoCA integrated routers were rolled out, NIM's became a hot commodity.
I still run a NIM, as I don't have a verizon provided router at all: I'm Ethernet to my own router and manage my entire network manually. I would strongly recommend AGAINST this path, as simple features like remote management of the DVR will become complex exercises in IP network management.