I’ve created this functionality in my “Happy Birthday To Who?” app. I had to use hidden inputs on-screen that break down the date based on the month number and day number. You can put a default value into an input and then use that value to update another parameter. So for each birthday, I have a month number parameter, day number parameter, and birthday date parameter.
If the first input is equal to the 2nd input, the birthdate falls in the same birth month.
Then do the same for days. 2 inputs that calculate the birthday day of the month and the current day of the month.
Use those as comparisons where the birth month is equal to the current month, and the birthday day number is equal to the current day. I have multiple lists on the home screen, based on when the birthday is approaching.