Yii2 Alphapager performs alphabetic paging with for instance
sjaakp\alphapager\ActiveDataProvider in stead of your normal
yii\dataActiveDataProvider, and put an
AlphaPager widget in front of your
GridView, and you're running.
Alpha paging is compatible with normal pagination. You can use them together.
Yii2 Alphapager's ActiveDataProvider is only proven to work with MySQL databases. It should also work with SQLite and Cubrid, but this is not tested.
In contrast to the Yii philosophy, Yii2 Alphapager is not transparent to the database, as I'm sorry to say. Presumably,
ActiveDataProvider can be made to work with Oracle, Postgres, and MSSQL as well. If you can provide more information on using Yii2 Alphapager with other databases, I'd be glad to hear it.