Finalize GST Invoice Config and Pre-Launch Audit

Hi, I have already built and configured my Greenshift Eco online store on Dukaan and am now preparing for launch.

I am looking for someone experienced with Dukaan + GST/e-commerce setup for a final GST invoice configuration and pre-launch audit.

Most of the setup is already completed, including:

Dukaan store, domain, design, navigation, categories and policies
Razorpay connected and payment successfully tested
Shiprocket connected with Dukaan
GST registration completed and GSTIN updated
Zoho Books set up for accounting
Google Business Profile approved
Initial launch products finalized and ordered

I mainly need help with:

Setting up and verifying the GST tax invoice format in Dukaan
Checking company name, registered address, GSTIN, invoice numbering, HSN and GST rates
Testing CGST/SGST and IGST treatment where applicable
Creating a test order and verifying the complete invoice calculation
Checking the Dukaan → Razorpay → Invoice → Shiprocket workflow
Checking refunds/returns, inventory deduction, checkout and customer notifications
Doing an overall pre-launch audit and identifying anything that needs correction

I am not looking for redesign or complete store development. The store is already built.

Please let me know your one-time fee, experience with Dukaan/GST stores, and what will be included in the audit.