Opencart/Journal v3 to v4 Website Upgrade

We need a freelancer to upgrade our existing Opencart v3 website from Opencart/Journal v3 to Opencart/Journal 4. - Upgrading website from OpenCart 3.0.2.0, Journal 3.1.12 and PHP 7.3.33 to the latest stable combination compatible with your required theme, extensions and hosting. - Preserving the current store design, with no redesign requested. - Preserving all existing store data, including approximately 641 products, 12,193 customers and 6,487 orders, together with the other existing store data. - Reviewing and retaining the required functionality of the installed extensions including Stripe, PayPal, ShipStation, USPS, Google Tag Manager, Facebook and Instagram, and testing the required integrations after the upgrade. - Keeping our IONOS US hosting and accounting for your LAMP/Plesk and Cloudflare setup. - Assessing, updating and testing our IONOS UK mirror and its synchronisation with our primary US server. - Checking for existing custom code, which is currently unknown, as part of preparing the migration. -We need this done without interruption to service on our live website