Fullcalendar - custom timeline and event slots for resource view "Rooms/Shifts"

Is it possible and how to achive such scheduler view:

There are always 2 shifts per day. Day/Shift is single slot for multiple events. We are using pro version with Timeline View

This is achievable.

Option "slotLabelFormat" controls how the time and date cells are labelled, here's an example:

slotLabelFormat: [
  { day: 'numeric', month: 'numeric', year: 'numeric' }, // top level of text
  { hour: 'numeric' } // lower level of text
],

Demo.

This allows to create 2 row header.

The "slotDuration" setting controls the size of the slots. This allow to split columns into 2 (or more) periods per day. If you need the shifts to be less than 12 hours you can change that and set slotMinTime/slotMaxTime to hide the other hours.

slotDuration: {
  hours: 12
},

And there is also "slotLabelContent" to customize the labels. It can be used same way as "content-injection". This can be function triggered each time label is displayed. This way hour label may be changed for shifts names or whatever is needed.

/** @param {SlotLabelContentArg} arg */
slotLabelContent: arg => {
   arg.level; // Label level
   arg.text; // Original label text - depends on slotLabelFormat & slotDuration
   arg.date; // slot Date object

   return arg.text;
}