Does LEGO no longer support NXT 2.0 at all?
LEGO officially stopped supporting NXT in 2015, however, as of 2019, the original NXT programming software is still available on the official LEGO MINDSTORMS web page.
The original NXT programming software and EV3 desktop programming software are both 32-bit, so cannot run on macOS 10.15 or later.
The new EV3 programming software based on Scratch does not work with NXT. So the only way to program NXT on macOS 10.15 is with 3rd party software such as NXC/NQC or leJOS or by installing a macOS or Windows virtual machine to run the old desktop software.