If you're a start-up and looking for a MVP especially in an eCommerce vertical market, we'd love to be involved.
We'd stress eCommerce as `partnership` because building and running a high-end on-line store is a journey and not a quick out of the box product. Your actual shop or its foundation won't take long to set-up, but if all you want is a vanilla store then just choose 'Shopify'.
We'd suggest a really powerful system, i.e. Magento [stress i.e. and not e.g.]. There is a reason the World's top e-Commerce sites choose Magento and while we can have a pre-installed template for you very quickly, its development is an investment and is truly bespoke or we'll make it that way.
You start with a theme [naturally] and then overlay on this, which is all done in custom PHP. There is a very powerful backend CMS and this is great for maintaining products, but we're talking about the workflow of the site and one which is unique to you. This is where a professional Web Developer is required and not just a Web CMS Manager. You need both, of course, and the latter is probably you.
It has to be said that post Magento 2.x a lot of the hard work in terms of customisation has been removed as many extension features are now standard, but Magento is not a vanilla product and it should really be made your system and that includes the back-end side and not just the customer facing shop-window.