The Apple Watch and the Siri digital assistant inside it; Inc.’s Echo speakers and Alexa service; the data about eating habits recorded by internet-connected refrigerators — all are potential targets in a European Union competition probe.

Regulators led by Margrethe Vestager said they want about 400 companies to contribute to a report about how so-called internet-of-things devices collect and use consumer data. The investigation follows years of relatively unchecked growth by technology giants into wearable devices and smart home products.

Vestager’s probe is likely to examine issues such as Siri’s preference for using Apple Music rather than Spotify Technology SA’s service, and Amazon could be questioned on why Alexa won’t let users change their default grocery delivery provider to a rival. Amazon and Apple Inc. make two of the world’s most popular voice assistants, and they’re baked into millions of home automation products. Both companies let competitors build for their ecosystems, but functionality is typically limited for third-parties compared to their default offerings.

Spotify Chief Executive Officer Daniel Ek said last year his music-streaming service has suffered “a big business impact” from such restrictions. Amazon came under fire a month later after Bloomberg revealed how contractors were listening to private recordings from its Echo products.

The market for smart, connected devices and their underlying ecosystems are “expected to grow significantly in the coming years” and it was appropriate to make sure competition is fair as they become “commonplace in the daily lives of European consumers,” Vestager said in a statement Thursday.

As the Silicon Valley giants add new services, smaller companies in industries like food delivery or fitness tracking could find themselves competing with the might of the world’s biggest tech companies and cut off from potential users.