You will need a working QNX2 system to create a QNX2 boot disk. QNX 4 will only read a QNX 2 disk. It can be tricky to find the hardware to run QNX2, but you can run under VM on a modern PIV if it has a floppy. Of course if you have a working boot floppy you can just copy it.
The interleave is not needed. The default formating QNX2 floppies was to put an interleave in because the driver only would read on sector at a time, and this enhanced performance. That is except at boot time when the boot loader would read multiple sectors in one read. So having the interleave slowed things down on a boot diskette.
If you need a QNX 2 boot diskette and don’t have one, you can check with QNX. I think they might supply one to an existing customer.
You might be able to get some help from one of the remaining consultants who still knows about this stuff. Off the top of the list is Ken, Mario, and myself. Apologies to anyone I’ve left out.