OK managed to convince mcuxpressoide-11.7.1_9221.x86_64.deb.bin to extract the deb files to the directory installer. Then using "ar" extracted the data files from the .deb files, and installed using tar.
So now running "mcuxpressoide" from the somewhat unusual path of "/usr/local/mcuxpressoide-11.7.1_9221/ide" and it fires up the IDE.
Now trying to install the SDK for the LPC845-BRK board and I get the error
An error occurred while installing the items
session context was:(profile=DefaultProfile, phase=org.eclipse.equinox.internal.p2.engine.phases.Install, operand=null --> [R]org.eclipse.jdt.core.manipulation 1.16.100.v20220513-2002, action=org.eclipse.equinox.internal.p2.touchpoint.eclipse.actions.InstallBundleAction).
The artifact file for osgi.bundle,org.eclipse.jdt.core.manipulation,1.16.100.v20220513-2002 was not found.
So what went wrong here?