SEO is a single tactic under a greater umbrella. Most technical SEO is handled out of the box by Shopify. If the brand is well established and huge you’re not going to beat them in the SEO game, so you have to beat them in a different game.
My favorite solution is focusing on great content for people, which will drive organic traffic.
Lean into one thing that works for you. Do you already have one blog post that does pretty well? Keep going. Can you create more articles on that topic? Can you provide it in different formats? Now imagine you are publishing content to your website two to three times per week. At some point you would overwhelm the competition with organic traffic and quickly become an authority in your space.
Creating this much content is not as intimidating as you think. You don’t want to be starting from scratch every single time. Take everything out of what you already have and create templates. For example, my podcast is recorded in audio and video. Then, I’m able to take snippets and make them social media posts. I also transcribe them and they get turned into blog posts. One podcast turns into several pieces of content.