I’m afraid it discontinued. The stylus tech of that device is the same as Chuwi hi 12 and Cube iwork 10 flagship but they are not compatible out of the box without some hacking. When i had my cube, both Cube and Chuwi pen got discontinued, so the reseller help me buy a teclast pen which took 1 month and he told me that it’s one of the last pen produced.
It seem like the pen source stopped providing to all of the OEM so they are all out of stock now. Your best bet would probably be buying off someone on this forum.