With that being said, GNUstep is still being worked on. It’s currently roughly compatible with Mac OS X Tiger’s version of Cocoa. While this is far behind macOS Catalina, I’ll be honest and say that Mac OS X Tiger with some security updates can hold its own against modern operating systems. There’s even a fork of Firefox called TenFourFox that’s available for PowerPC Macs running Tiger.
What I personally believe is that GNUstep needs a suite of compelling applications in order for it to be more strongly considered. There are a lot of GTK and GNOME applications, and there is also a compelling collection of QT and KDE applications, but where is there a GNUstep web browser, office suite, image editor, photo library manager, etc.? GNUstep is less compelling in a world of GTK and QT apps. But if more GNUstep applications were written, then that may convince other developers to put in the work necessary to create a desktop distribution based around GNUstep and it’s applications. I was impressed by the now-defunct Étoilé project which attempted to revamp GNUstep in many ways.
Anyway, I still think GNUstep has some potential, and there’s a window of opportunity for the project to gain more support, especially in an era of increased disappointment over Windows 10 and macOS.
I'm not sure why the releases are so infrequent though as it has been almost three years since the last one.