Add a day "0" to the Date Picker (ie 0/6/22)

I have read several other posts on this topic but haven't quite been able to get what I want to happen without going through a complicated workaround.

Here's the problem: I need to display the date for a bunch of documents but unfortunately some of them don't have days listed, only month and year.

Can I add an additional day to the Date Picker with the value of "0" - that way if someone selects "0" I can show just the month and year, rather than the whole date?

I've done a workaround by creating three (hidden) columns corresponding to Day (choice), Month (choice) and Year (choice), then using a calculated column to combine them like so:

=[Publication day]&" "&[Publication month]&" "&[Publication year]

This is a pain in the neck because I'm going to have people fill in a Microsoft Form when they upload documents and they will have to answer three separate questions (one for Day, one for Month and one for Year) to get the correct information into Sharepoint (plus it's annoying for me to have a lot of columns to enter information into as well).

I did consider having people set the day to the first of the month in the date picker if they didn't know the exact day the document was published and then just pulling the month/year from the result but I've been told that I need to be more specific.

Hopefully this post makes sense!

Thanks so much.