Android: Are there xxxhdpi density devices?

New phones already use XXXHDPI. Our test phone Samsung S6 Edge use xxxhdpi drawable resources. Someone already mentioned that Nexus 6 also using this dimension. Thus new phones with good screen should use this dimension.

Are there xxxhdpi density devices?

Afaik Nexus 6 is xxxhdpi device

Just for reference purpose, now Google maintain a list of devices density and other information at https://design.google.com/devices/ which is mainly targeted for material design guideline.