Upon installation of Kclock, items Timers, Alarm, Stopwatch should also be available in Klauncher which would open Kclock in the appropriate tab. This could be achieved with addition .desktop files if the GUI app would allow using a flag to open in the specified tab.
Implemented now https://invent.kde.org/utilities/kclock/-/commit/55f66a796fdc86bef7434cb6b7ec26607b60b1ff
Oh , I didn't even know there already was a --page param - that made it easy. Thanks so much!