Yes! lightning.kokkos is still an active plugin. Itβs not yet on the PennyLane Install page but it is indeed an active plugin.
You can install it by running pip install pennylane-lightning-kokkos
Let me know if you have any additional questions!
Edit: If you just run pip install pennylane-lightning-kokkos it will work, but only with CPU (OpenMP). To have it working with GPU devices, for example, you would need to build from scratch so the compilation can configure everything regarding your local hardware. The full installation instructions are here in the documentation.
Unfortunately we do not currently release prebuilt wheels for Lightning Kokkos on Windows. If you have access to WSL on Windows, you can install the pre-built Linux versions with OpenMP support directly using pip.
If you wish to manually build the project under Windows, I suggest reading the installation guide here. Since Windows natively provides a much older version of OpenMP than Linux, you may have trouble compiling with the default backend, in which case you can attempt to use the Kokkos threads backend with -DKokkos_ENABLE_THREADS=1. Though, once again, this may not be fully supported under Windows or by Kokkos as well as the OpenMP backend.
Otherwise, if the above fails, you may be best to use the lightning.qubit device, as this will be guaranteed to work under Windows.