I just added support for CTABLES to PSPP. It is already available through the autobuilder at https://benpfaff.org/~blp/pspp-master/, including a flatpak build. I guess that the autobuilder at https://caeis.etech.fh-augsburg.de/buildbot/#/builders will also have a build soon.
Most CTABLES features are available and I have tested them. The following features are not implemented: - Multiple response sets - SIGTEST - COMPARETEST - Summary functions: * .LCL and .UCL suffixes. * .SE suffixes. - CATEGORIES: * Data-dependent sorting. Please try it out and let me know, especially if one of the features not implemented is important to you or if you find a bug.