It turns out Microsoft was working on a smartphone codenamed "Vela", that had a bezel-less design, way before Samsung, Google, or Apple had the idea.
If the phone would have been released, it would be a budget Lumia 435 for under $200.
The phone was probably developed even before Xiaomi released its bezel-less Mi Mix, which helped the more powerful smartphone giants see the value of the bezel-less design.
Who knows, maybe that phone would have saved Windows Mobile OS.
Windows Central has a full report on that phone with some pictures, https://www.windowscentral.com/microsofts-canceled-all-screen-lumia-handset?utm_source=wpc&utm_medium=twitter