A one-product store can be tricky and I can provide some pointers on things you can focus on when you are running such a store.
1. Choose a suitable theme: Find a theme that is designed for single products. Themes like these would give you a good number of content grids to work around with
2. Add buy CTA throughout your website
3. Talk in detail about your product. Cover the main features on the home page and include more sub-pages for further reads.
4. You can include content like comparison with other products and physical/application wise features that set your product apart
5. Do include a lot of high-quality media. Based on the type of product, including videos/gifs and images explaining different characteristics of your product.
6. You can also include bundles of your product if it makes sense. 2 pack, 5 pack etc. Would help you upsell your product
You can visit sites like ThemeForest to find premium Shopify themes for single-product stores.
I hope this helps and wish you all the best for your new endeavor!