Timeline event count using hours scale (Scheduler)

Yes, this is possible.

The code from the Column Summary and Availability Chart tutorial uses the real cell size (args.cell.start and args.cell.end) to calculate the utilization (total number of events):

onBeforeCellRender: function(args) {
  if (args.cell.resource === "summary") {
    var events = dp.events.forRange(args.cell.start, args.cell.end).length;

    args.cell.backColor = "#ffffff";
    args.cell.areas = [
      {left:0, top: 0, right: 0, bottom: 0, style: "display: flex; justify-content: center; align-items: center;", text: events},
    ];
  }
}

This means it will work correctly if you change the timeline scale (even for a manually-defined timeline).