Using UID column for API Resource routes instead of ID

sure it can - you will have to save that value yourself (by hooking into saved event or in your save controller method etc).. if you mean route model binding then you just need a func in your model to let laravel know (check the doc for func name)

You can use an where argument in your Eloquent model in combination with firstOrFail to return an row based on the uid.

Route::get('model/{uid}', function ($uid) {
    return App\ModelName::where('uid', $uid)->firstOrFail();
}

If the UID can't be found, a 404 HTTP response is automatically sent back to the user.

Thanks so much for the help. I ended up doing this in my model:

public function getRouteKeyName()
    {
        return 'uid';
    }

And now everything works exactly like I want including my tests.