Shopify Product Page

I'm looking for a professional Shopify developer who is able to add the following to my product page through the use of highly optimised code, to ensure that the load time remains light and super quick, especially on mobile.

- Sticky button and menu on mobile (when you scroll down, these will pop up)

- Size chart functionality (able to select a size chart to show per each product)

- Product variants (able to list each product multiple times based on color variant - e.g. "T-Shirt - Pink", "T-Shirt - Blue", etc). Also needs to show a different gallery per color option selected, etc.

- Estimated delivery time (integrate a pop up that shows all of the estimated delivery times with dynamic dates. E.g. if the delivery time is 2 days, it will say: "2 days (estimated 12th June)")

- Product description (style it, so there is read more/less)

- Add some product tiles (cross sells) - I need to be able to select a collection to show per product. E.g. product 1 might show collection A

- Review app (Add a review app and customise it to reach the desired functionality)

- Other tweaks etc

Please only apply if you have experience with shopify, are an actual developer (not just install some apps and call it a day), and are able to keep the code highly optimised.

Full specification will be sent to successful applicants.

Thank you.