Numba does not currently support generating NVVM IR required for UDF support. As a workaround, LLVM IR is used for GPU targeted UDFs, but that approach is just waiting for an example case that will fail due to some LLVM IR feature that won't work on a GPU. This issue has been reported in numba:
https://github.com/numba/numba/issues/4546
and the feedback from numba devs is constructive in the sense that they agree that the issue needs to be fixed because there are other use cases other than in omnisci UDF support where this issue is important to get resolved.
Numba does not currently support generating NVVM IR required for UDF support. As a workaround, LLVM IR is used for GPU targeted UDFs, but that approach is just waiting for an example case that will fail due to some LLVM IR feature that won't work on a GPU. This issue has been reported in numba: https://github.com/numba/numba/issues/4546 and the feedback from numba devs is constructive in the sense that they agree that the issue needs to be fixed because there are other use cases other than in omnisci UDF support where this issue is important to get resolved.