UPC is only using it’s own DOCSIS Cablenetwork. DSL is via phonecable, DOCSIS via TV-Cable.
There is no Fiberoptic offer from UPC.
My guess would be: Even after the merge with Sunrise, they won’t use Fiber, because one reason for merging is the own cablenetwork UPC has. Sunrise even want’s to attach the mobile antennas via this network. So probably no fiber option in the future from UPC Sunrise.