rapids-singlecell has some CuPy kernels for sum, mean_var, and so on. Our current CuPy support as of #51 is probably much slower. - [mean_var](https://github.com/scverse/rapids_singlecell/blob/main/src/rapids_singlecell/preprocessing/_kernels/_mean_var_kernel.py?rgh-link-date=2025-03-10T13%3A34%3A30Z) - [to_dense](https://github.com/scverse/rapids_singlecell/blob/main/src/rapids_singlecell/preprocessing/_kernels/_sparse2dense.py?rgh-link-date=2025-03-10T13%3A35%3A45Z)
