Migrate commerce products
A migration has the following required components:


A source plugin, which provides the data to the migration system from D6/7, a CSV file or whatever it is it connects to.
A destination plugin that stores data in Drupal 8.
The migration config entity that connects the two by defining the mapping and any processing/transformation of those properties/values.


The destination plugins are provided for all entity types in a generic way. So you can import data into D8 commerce products. However, what's fairly certainly still missing is source plugin that reads data from a D7 site. You can implement that yourself, it's fairly easy and there are plenty of examples for node, user, .. in core.

The migration entity is then also something that you need to define since that won't exist either. Depending on how different the data is, this is often the complicated part and needs possibly various transformations/process plugins to re-structure the data for D8.

For an example, see the migrations the we are in the process of writing for simplenews.