A store that is hard to check out of is a store that does not sell. Most of the work is in the last three clicks.
Build Your StoreTraffic is not the hard part. Getting somebody from interested to paid without losing them is, and that is where the build should spend its effort.
Shopify, WooCommerce, or custom, chosen for what you sell.
Fewer steps, fewer fields, fewer abandoned carts.
Stripe and card processing wired in, with tax handled correctly.
Stock accurate between your store and wherever you actually count it.
Recurring billing when what you sell repeats.
What sells, what does not, and what people almost bought.