Awesome, thank you for the input! That would be great, but I would feel bad if you had to go out of your way for all of that. I will mess around with that tomorrow and see if we should implement your suggestion for SharePoint!
As for the calendar component, I used whichever is set as a standard template in Power Apps under the new page selection.
I thought of a potentially easier solution in the mean time. Instead of searching for the date and vehicle to compare separately, I could just search the table on that day for subject (ie. Vehicle). If it contains that vehicle, then I could either disable the ability to choose it, or just give warning messages for each vehicle separately. Would you know how to do that?
Given the date for instance like a random dd/mm/yyyy, just use that to view the event on that day and if it contains the vehicle it satisfies or un-satisfies a condition. This is what I have gathered so far, but do not know how to insert the selected date chosen in that first picture I posted above into this function. I am pretty sure I will find more bugs, but right now its issue is I only have 1 argument when it expects 2-3.
If(
Filter(
Lookup(
Office365Outlook.V4CalendarGetItems(
Lookup(
Office365Outlook.CalendarGetTablesV2().value,
name = "Calendar",
id
)
).value,
"Vehicle" in subject,
id
)
) = "Vehicle", true)
