Yeah, it's the kind of thing that could be really useful, just nobody has really worked on it as anything more than a proof of concept. The general cost of VR is still prohibitive, after all.
The best bet is either a 3D printed gun sight, or maybe attaching a sensor to an existing gun shell, depending on the tracking system. The quest has some pistol grips you can buy that you might be able to stick some rudimentary sights to and use as a pretty handy wireless gun. In terms of software, something based around OpenVR would be best for the widest compatibility, like with
https://github.com/asingh57/openvr_lightgun. That, combined with an on screen calibration tool and the standard "shoot the targets" to dial in the cursor, line of sight offset for sight picture alignment, and as a virtual joystick or mouse driver implementation so you could use it in all the games, would create a pretty good system with low latency and any distance tracking, with accuracy being dependent on the tracking system used.
But it's a lot of work for a fairly niche application.