We've spent months with barely any example use of Google's Nearby API by third-party apps, but in only a couple of days several apps have popped up with this proximity sharing method. First it was Radon for sending regular links, then Card Case for contact details, and now it's app links' turn with an app called, predictably, App Links.
The app was just updated to version 2.0 and it no longer only supports sending links of your preinstalled apps with Android's Share intent. There's a new Nearby icon in the app's title bar (which looks like two overlapping playback buttons) that simply broadcasts the apps you have selected to devices that are close to you, and looks for apps being shared back by them.
Like all instances of Nearby, both devices have to have the app installed, and once you select the apps you want to share, you only have to tap the Nearby icon and allow App Links to use it. The screen will populate with links that are shared by nearby devices and you can tap any one of them to take you to the Play Store to grab it.
It's as simple as it gets and another great use of the Nearby API. It's also free and ad-free.