Overall, this is relevant not just for e-commerce but for all products that are online. In the SaaS field, web design also plays a huge role. In general, everyone always puts functionality first, especially in SaaS, and that’s understandable, but I highly recommend setting aside budget for design and for UI/UX specialists right away. If you’re curious how it works, try here, talk to top specialists, tell them your idea, how you see the site, your product, so it’s easier to find the right solution.