Please Note that OTA features are not supported in this release as was mentioned in the announcement. Please do not try to apt upgrade your Jetson to JetPack 6 Developer Preview release. Use SDK Manager or manual flashing to install JetPack 6 Developer Preview.
We will release the SD Card image for Jetson Orin Nano developer kit today. Please note that, since QSPI bootloaders have moved to a new major version, you will need to at least once install JetPack 6 using SDK Manager or manual flashing in order to update the QSPI. After that you can use JetPack 6 SD Card image.