Track acquisition channels for 302 redirects (/app) to app stores

We created a smart link unblnd.com/app

This link detects the device: desktop, iphone, or android. Depending on the device it goes to the main page or the specific app store.

The link is a 302 redirect which is not indexed.

Goal: Include the /app redirect route within google analytics and track the acquisition channels

Ideas:

• change unblnd.com/sitemap.xml
• do not use redirect, just go the mainpage
• use google tag manager
• some third party

Is there some clean, easy approach which is considered best practice?

More info:

To create the redirect we use this Laravel controller method

routes/web.php

Route::get('/app', 'LandingController@app');

LandingController

public function app(Request $request)
    {
        if (!Agent::isMobile()) {
            return redirect('/');
        }
        else if(Agent::isAndroidOS()) {
            return Redirect::away(config('app.android_url'));
        }
        else if (Agent::isIphone()) {
            return Redirect::away(config('app.apple_url'));
        } 
        return redirect('/');
    }