A minimal B2B portal allows customers to place orders and to track the status of orders. A portal is, of course, a website. The Dear B2B portal offers some basic flexibility for designing layout and adding content pages. It's not going to win any awards, but it does the job.
Customers need an invitation before they can place orders. You do this by adding a contact to the customer and then inviting them.
Orders enter Dear as authorised quotes. The portal lets customers see order history and status.
The portal currently does not have payment integration so you can't offer new payment methods. The order status shows the customer the payment status.
You can show no stock levels or show in/out of stock or show actual stock levels. You can limit this to a particular warehouse.
Bottom line: it's easy to setup (a couple of hours at most to get up and running), it's free, and it automates basic order enquiries and order entry. You control which customers use it. If both of these are low added-value steps, it's worth looking at this. You can treat it as an experiment. If you see more potential in this than you expected, you may decide to get more serious and invest in a dedicated solution. Potentially it's useful for reps on the road, too.
Configuration is via the Integration tab.
It's under development and payment integration at least with international players (Stripe/PayPal) is promised. Here is a Dear tutorial from October: there have been some updates since then.
Dear also has a POS solution, which is still in beta.