Shopify app fixes

I have a Shopify app (Wrapely) currently in review and need an experienced Shopify app developer to fix issues flagged by Shopify.

Tasks include:
- Remove all off-platform billing and correctly implement Shopify Billing API / Managed Pricing
- Fix subscription sync (plan changes not updating correctly)
- Ensure full embedded app experience using Shopify App Bridge (no external redirects)
- Fix UI bugs (loading issues in integrations section)
- Add simple theme customization/presets (basic UI options)
- Add App Store submission guidance section inside the app
- Ensure everything meets Shopify App Store requirements for approval

This is NOT a basic Shopify store job — I need someone experienced with Shopify apps, APIs, and app store approval process.

Please send examples of Shopify apps you have built or worked on.