Change the product price based on store id

functions.php

<?php 

// this goes in your theme functions.php file

function my_custom_product_response( $response, $product ) {
  
  // early exit if user is not in the POS
  if( ! is_pos() ) {
    return $response;
  }
  
  // get the old product data
  $data = $response->get_data();
  
  // get the current logged in store id
  $store_id = get_user_option( 'woocommerce_pos_store' );
  
  // change the price based on store id
  if( $store_id == 1234 ) {
    $data['price'] = '2.99';
  }
  
  // reset the new response data
  $response->set_data($data);
  return $response;
}

// filter the WC REST API response
add_filter( 'woocommerce_rest_prepare_product_object', 'my_custom_product_response', 10, 2 );
add_filter( 'woocommerce_rest_prepare_product_variation_object', 'my_custom_product_response', 10, 2 );