I'm willing to test it on Remix OS on my desktop.
Although as a warning, I barely have any time lately, so results could arrive after some time.
There is also Android-x86, which I'm sure that someone could use for testing.
About Remix OS, I'm sure you know, but it's API22.
Android-x86, again I'm sure that you already know, has both API22 and 23 (6.0.1RC).
Pheonix OS is also API22.