(how) Is it possible to have the Eddysone-URL provide functionality, similar to NFC, that would have the user only within a close proximity be able to get the URL?
I've been testing using the eddystone-beacon library on the Intel Bluetooth 4 enabled Wifi card to send the signal successfully. But I find that I can receive the signal from far (20+m) away, when I'd like to limit it to within one meter.
The library has options to attenuate the power txPowerLevel: -22, // override TX Power Level, but I find that changing this only messes with the distance calculation, and not the ability to receive the signal.
Is this perhaps an issue with the hardware (maybe a dedicated USB would allow control?)
Eddystone-URL is not designed to work this way using Google's standard services. However, it is possible to do what you want if you have a dedicated app on the mobile device that detects the beacon.
If this is an option for you, then you won't want to reduce the transmitter power on your hardware device. Even if you get hardware that allows this, sending a very weak signal will lead to unpredictable minimum detection ranges of 3 feet or more on devices with strong receivers, and not detections at all (even if touching the beacon) on devices with weak receivers.
Instead, leave it at the maximum transmission power and then filter for a strong RSSI on the receiving device, showing the detection only when the RSSI meets a threshold. You'll still have trouble with varying strengths of receivers, but it is much more predictable. I have used this technique combined with a device database that tracks the strongest signal level seen for a device model, so I know what RSSI a specific device model will detect when it is right next to the beacon.
If you are game for this approach, you can use the Android Beacon Library to detect Eddytstone-URL for your app on Android devices and the iOS Beacon tools on iOS devices.