Re: Windows XP and MPLABx versions for PIC18F26Q10
The PIC18F26Q10 is a relatively new device released after MPLABX IDE V3.2, that's why it's not listed.
You will need a relatively new version of MPLAB X IDE to support it (you could try checking from v5.xx).
You must also remember that MPLAB X has not been tested on XP operating systems for several years now it may or may not work, it's up to you to try if you will have some luck.
As you know windows XP support had been officially dropped by Microsoft since 2014, you can't expect to use a newer device with old software/operating system, you will need to upgrade your machine to make your life easier.