Known supported Android versions:
Marshmallow, Nougat (official 7.0 & 7.1), Oreo (LineageOS), Pie (unknown)
Unsure if any future support by Razer (which purchased Nextbit in 2017) is planned. My own device is still running a Nextbit-provided Nougat 7.1.1.
Other known issues: none that I’ve run into. I’m also not a developer.
Cheers.