TVM main branch has removed the Relay frontend.
And it is claimed that the Relax Onnx frontend supports all operators that Relay could support: Phasing out Legacy Components - #20 by Hzfengsy
yes, the newest code delete all nms implementation include topi, rencently we need the nms in relax model support, so porting one kind of nms to relax, i think we can upstream it. @ysh329