I use the GCal search app for functionality like this.
Even though the support is withdrawn for the app, it is still functioning great.
I have several searches set up and then they act just like a switch that can be used as a condition or trigger within a piston. For example, I wake up at different times during the week. I have a “Wake Up” event on my calendar each day. I have a GCal search for “Wake Up” and that triggers mywake up piston to run whatever I want. I also have GCal searches for birthdays, anniversaries and even sport’s teams.