It seems as though the company has ambitions beyond the PC versions of the platform and is also working on browser extensions for Windows 10 Mobile.
Microsoft's upcoming Edge extensions will be landing on the browser in the next few weeks, courtesy of a Windows 10 Redstone preview update, at least if you are part of the Insider Program.
However, the browser extensions for Windows 10 Mobile are likely to come later, probably even after the full Redstone build lands in June.
Long time users of Windows Mobile and Windows Phone will know well enough that sometimes you have to wait a long time for something that Microsoft may say is just around the corner.
During BUILD 2015, when Microsoft introduced Edge to the bigger public, Sean Lyndersay and Charles Morris, both working for the Microsoft Edge team said that bringing extension support for Edge on Windows 10 mobile was part of Microsoft's plans. As Lyndersay stated they “first need to bring them on the desktop version of the browser,” while Morris added that “it's harder to make them work on a 4-inch screen” because extensions could also add new buttons and change the UI of the browser.
“Coming soon” rarely means quite that with Redmond, and there has been no official comment that Edge extensions will be coming to mobile devices at all. However, the appearance of ARM support for extensions shown in the Redstone preview show that mobile devices are likely to be supported too.
Microsoft has certainly said in the past that extensions would land on desktop Windows builds first, before heading to the mobile ecosystem later.
Luckily, all these unanswered questions, including those regarding Windows 10 Redstone in general, will all be answered during Microsoft's 2016 BUILD Developers Conference, which gets underway next month.