Example custom product response for POS Stores

functions.php

<?php 
/**
 * add to your theme functions.php file
 */
function my_custom_product_response( $response, $product, $request ) {
  // only intercept requests from the POS
  if( ! function_exists('woocommerce_pos_request') || ! woocommerce_pos_request() )
    return $response;

  $store_id = $request->get_param( 'store_id' );
  $product_id = $product->get_id();
  $data = $response->get_data();
  
  /**
   * This is the important part: using the POS Store ID and the Product ID you 
   * can look up the stock quantity value. This will depend on your inventory plugin.
   */
  $data['stock_quantity'] = '';
  
  // Save the updated response
  $response->set_data( $data );
  return $response;
}

// get the product respense priority 20 (after default POS code)
add_filter( 'woocommerce_rest_prepare_product_object', 'my_custom_product_response', 20, 1 );