A developer from Ukraine going by the 4PDA forum name "B-S-G" recently created and published a modified version of the Google Camera application, effectively giving HDR+ capabilities to smartphones other than Google's Pixels. The application is compatible with any device which is powered by the Qualcomm Snapdragon 810, Snapdragon 821, or Snapdragon 835 system-on-chip, and it can be side-loaded as any other APK file without root access.
The Google Pixel smartphones have one of the best mobile cameras around, at least according to some experts. The phones previously received a top score in DxOMark, surpassing devices like the Samsung Galaxy S8, OnePlus 5, and the LG G6. Technically speaking, the Google Pixel camera is of the 12.3-megapixel variety, has an aperture of f/2.0, and takes advantage of numerous technologies including phase detection and laser autofocus, EIS, and a dual-LED flash. However, one of the best camera technologies available on the Google Pixel smartphones is HDR+, which allows users to capture well-lit, sharp, and generally high-quality images regardless of their first-hand experience with manual photography. Google's exclusive HDR+ technology is evidently available only for the Pixel smartphone series, however, with the modded Google Camera application developed by B-S-G, the HDR+ function can now be experienced on a wider range of smartphones as long as they take advantage of the Hexagon 680 DSP (or above), which is currently only present in Qualcomm's last three high-end mobile chips. With that in mind, the modded Google Camera app should be compatible with smartphones like the OnePlus 3T, OnePlus 5, LG G6, and some iterations of the Galaxy S8 series.
The modded Google Camera app is based on the Google Camera application initially released in the third Android O Developer Preview published in June. It can be installed on compatible devices running the appropriate system-on-chip even without root access, as long as the smartphones are set to allow the installation of applications from unknown sources. With that being said, while the newly released app seems to be perfectly safe, side-loading apps is something that you're always doing at your own risk and no one other than you will be responsible in case anything goes wrong.