I don't like Facebook any more than you but to be fair, they're not as bad as they could be. For on-device software sideloading is available and SideQuest makes it pretty functional. Additionally, the device supports OpenVR and can be used with any software you'd like to run on your desktop PC.
It's more the Google approach to the ecosystem than it is the Apple approach, though I don't believe the OS is open-source.
You need a Meta account. Not a Facebook (social network) account.
Meta accounts only require an email address. There is no real name requirement, which they explicitly state in their help page[1] so this isn't a violation of the TOS.
This isn't a monitor though, it's another standalone computer that you're streaming an image to. The wired connection option isn't using DisplayPort or HDMI signaling over USB-C, it's establishing a network connection over the USB link and then streaming video over that in the same way as it would over WiFi.
VR headsets that don't contain their own processing on the other hand do in fact work like a normal monitor. Usually they'll go in to a "direct mode" that does not appear as a monitor when their drivers are installed for both performance and convenience reasons, but they can be configured to just appear as yet another monitor.
You must be young, that was exactly how things were for decades. Its just that it was called a driver, not an app but in effect it was same piece of software that unlocked the device for use. For monitors, often without proprietary driver, it would work only on some default vesa resolutions, not support all available refresh rates etc.
A monitor driver, at least in the form most people remember dealing with on Win32 systems, wasn't even a piece of software. It was just a .INF file containing the Windows equivalent to X modelines describing what modes and was only necessary if you either didn't have working EDID for whatever reason or wanted to go outside the range the monitor advertised working at.
Before these "drivers" had to be signed it was common for various graphics tweak tools to provide a method for building your own custom INF to "overclock" a monitor that only officially supported 60 Hz or whatever.
It's more the Google approach to the ecosystem than it is the Apple approach, though I don't believe the OS is open-source.