Article 21
Cases in which obligations of manufacturers apply to importers and distributors
An importer or distributor shall be considered to be a manufacturer for the purposes of this Regulation and shall be subject to Articles 13 and 14, where that importer or distributor places a product with digital elements on the market under its name or trademark or carries out a substantial modification of a product with digital elements already placed on the market.

For context, see recitals:

• Recital 39: Substantial modification triggers