For those who don’t know, a birthday calendar is a monthly calendar, where the days are listed vertically, often in two columns.
The day of the week is not relevant on a birthday calendar, because it’s a calender that’s used for many years. I guess on a digital version we might as well have them.
Traditionally, a paper birthday calendar is hung up in the loo, and remains there for many years. Ideally someone flips it over every first of the month, to reveal the next month’s birthdays and anniversaries and whatnot.
Here’s an example of what one looks like:
https://www.bol.com/nl/nl/p/verjaardagskalender-zwart-wit-prints-charming/9200000071817182/
That one is pretty basic and overpriced, but it serves as a good example of what one in HA might end up as.
Now, a birthday calendar view doesn’t add anything significant or functional to the existing month view, except for familiarity with pre-existing paper birthday calendars, which has to count for something. It’s just a different way of viewing the same data.