Ultimate Shopify SEO
This is a fantastic reference article on advanced SEO for Shopify sites – https://www.digitaldarts.com.au/the-expert-guide-to-shopify-seo . Make sure you read to the bottom for the juicy bit.
Combine it with https://www.gsqi.com/marketing-blog/how-to-redirect-images-during-website-redesign-or-migration/ – ie, don’t forget to do redirects for your images too.