PHP Carbon diffInWeekdays alternative to return float instead of int

I'm working on a leave/holiday management system.

As well as booking full days leave/holiday they can book half days (morning or afternoon off).

I need to calculate the total amount of days during a requested period. 3 and a half days would be presented as 3.5

To make calculations easier for half days, the maths is based on a day starting at 00:00 and ending at 23:59:59.999999

I can do this with the following but it doesn't exclude weekends which are counted as part of a users leave quota.

if($validated['leave_start_day_part'] == 'AM'){
    //Leave starts at the beginning of the day 
    $startDate = Carbon::createFromDate($validated['leave_start_date'])->startOfDay();
}else{
    //Leave starts midday (half day)
    $startDate = Carbon::createFromDate($validated['leave_start_date'])->midDay();
}

if($validated['leave_end_day_part'] == 'AM'){
    //Leave ends at midday (half day)
    $endDate = Carbon::createFromDate($validated['leave_end_date'])->midDay();
}else{
    //Leave ends at the end of the day
    $endDate = Carbon::createFromDate($validated['leave_end_date'])->endOfDay();
}

$dayCount = $startDate->copy()->diffInDays($endDate);

diffInDays returns a float which is perfect but also includes weekend days.

However if I switch that to the following it returns a whole integer (3.5 is returned as 3)

$dayCount = $startDate->copy()->diffInWeekdays($endDate);

I've considered using diffInDaysFiltered but that also only returns an integer. The decimal is crucial to calculate the total used leave. Is there another method of Carbon that can achieve this and output float or is it time to consider another route?

There isn't any other function that will return a float. However, diffInWeekendDays is an option. Take your current number of days, and subtract the result of that function.

$weekend_days = $startDate->copy()->diffInWeekendDays($endDate);
$dayCount -= $weekend_days;