iMac late 2009 can’t install anything past macOS Catalina

So I did the Dosdude patcher to get up to Catalina since the open core patcher doesn’t support Catalina but now I can’t seem to use open patcher to install MacOS big sur cause one of two things happens either gets stuck trying to find an update and fails or it fails to install the update, so I don’t know what else to do to get it working