Navi just began to compile a week or two ago. Still 'unsupported', but its slowly gaining features.

ROCm is a bit uneven with what cards it supports. Ex: Rx 550 never was supported (even though Polaris, the rest of the 5xx series worked). It seems like the only cards ROCm works for are the ones that share a chip and/or driver with AMD's "Machine Intelligence" line of cards. (MI50, MI60, etc. etc.). Which are Fiji (Rx Fury), Polaris (Rx 580), Vega, and Radeon VII.

CUDA is a "works on all NVidia devices" kind of thing. So I think people are surprised when they have to read the docs for AMD's ROCm.