the updated night mode (4 seconds one) seems to be a better HDR, if you want to wait 4 seconds that isAlso, the HDR mode is literally broken in this phone, 90% of the time I get better shots on Auto, and HDR mode always crushes blacks in almost every scenario I use it, so I stopped using it completely and trust Auto. (This maybe has to do with the monochrome sensor information, since you always get perfect exposures with the monochrome sensor, you probably never gonna need the HDR mode by itself..)
but the google camera port's HDR+ works for me and it "seems" to give better HDR results than default camera's hdr. I get better detail in the darker areas but the color is off to me, but since I can't see certain shades of color, I don't know how "off" I am. It's really mostly less vibrant for a color, a photo editor might be able to bring back the color but I don't do this either.