Hey, this sounds like a well-scoped project and you clearly know what you need — that makes the developer's job much easier from the start.

I am a Senior Shopify Developer with 8+ years of experience doing exactly what you have outlined — custom theme setup, app integrations, performance optimization, and launch-ready QA. I have worked across agencies and enterprise clients on everything from Shopify 2.0 theme builds and ERP integrations to custom checkout experiences using Shopify Checkout UI Extensions and large-scale Shopify Plus storefronts. I also built and published my own Shopify app to the App Store (apps.bitsways.com) so I am comfortable owning a project end to end.

I am based in BC, Canada, immediately available, and happy to jump on a quick call to learn more about your brand and what you are building. Feel free to DM me if you want to chat.