Jetson Nano supports managed memory. The reference document was already provided by cbuchner1.
In general, support for managed memory is a query-able device property that can be retrieved with e.g. cudaGetDeviceProperties and in fact is one of the items displayed in the deviceQuery sample code.
Jetson managed memory does not allow concurrent access. Therefore, you should remember to issue cudaDeviceSynchronize(), sometime after launching kernels, and before you intend to access managed data in host code.