Views

Due to a limitation in the Drupal 8 views module, #2079019: Make Views use SqlEntityStorageInterface, the external entities can't naturally be used in views directly.

There are still some options, however:

• There is an External Entities Views Plugin module for v2 that may have devised a way around. This module is integrated into v3 as a companion module that needs to be enabled to have views integration.
• By using the search API module it is possible to build views around the indexed external entities.

Since external entities are "external" to Drupal, it may not be very efficient to use external entities directly into views. However, in some cases, it can be relevant to do so, for instance to query local files or local external databases. Therefore, you may try to use the external entities views support and use the search API module instead it is more efficient.