Hello!
No, unfortunately the LPU-1 cannot be used as an extra CueluxPro interface or as a 3rd universe for CueluxPro

The LPU-1 belongs to the Cuety system, so it works as its own separate 1-universe controller with the Cuety app. It does not unlock or add universes inside CueluxPro.
For CueluxPro you would need a supported interface like a CueCore or QuadCore. Your CueCore 1 gives you 2 universes in CueluxPro, so for a 3rd universe in the same CueluxPro show you would need another CueCore/CueCore2, or a QuadCore/CueCore3 depending on the setup.
Also, don’t plan on daisy-chaining this through the CueCore. Put the devices on a normal network switch and assign the universes in CueluxPro.
Hope this helps!