The building of the nxusb module on Ubuntu 26.04 doesn't complete because of missing kernel headers:

/usr/src/linux-headers-7.0.0-15-generic/include/linux/kconfig.h:5:10: fatal error: generated/autoconf.h: No such file or directory

As a consequence, USB forwarding will not work inside the NoMachine session.

Possible workaround to compile and place the nxusb module:
Step 1: Clean the NoMachine directory first. Navigate to the source directory and clean any leftover build files:

cd /usr/NX/share/src/nxusb
sudo make clean

Step 2: Restore your system kernel headers. Now that the cleanup is done, reinstall your headers to restore the missing autoconf.h file:

sudo apt update
sudo apt install --reinstall linux-headers-$(uname -r)

Step 3: Manually build and deploy the module. Run a fresh compilation:

cd /usr/NX/share/src/nxusb
sudo make -C /lib/modules/$(uname -r)/build M=$(pwd) modules

Step 4: When the module has been built and successfully loaded, copy it to the drivers directory:
sudo cp nxusb.ko /usr/NX/bin/drivers/