One way to assess someone's grasp of the product is to conduct a role-play where one participant tries to sell the product to another. As a sales training role-play, it can be useful to run a few different role-plays where the potential buyer knows more or less about the product to see how the discussions progress.
Once you have the role play scenario thought out, the next step is to choose which of the activities available online are suitable for the delivery.
There are multiple ways to run such role-playing online:
You can use a real-time audio tool, where people speak but have no visual cues
You can use full video conferencing, where the visual aspect always comes into play
And you can use a text chat where there is only what is written, and no audio or visual cues
Moodle integrates with a wide range of third-party conferencing software which can cater for the first two scenarios, but it has a very strong real-time chat activity which is suitable for tackling the third...