Adjust precision (Year, Month, Day, Time) of iCloud Photos EXIF metadata?

I'm importing a number of older non-iPhone photo collections into my iCloud Photos Library via the Photos app on my Mac. These were taken either on early digital cameras or are from scanned film.

In some cases, the photo EXIF data is correct and all of the original timestamps are imported into Photos correctly.

In other cases, either the EXIF data is obviously incorrect or the photograph's date is set as the Unix epoch timestamp of January 1st, 1970.

In many cases I know the Year and Month of the photo. In some cases I can deduce the correct date. In some older family photos I only know the year, or want to set a "circa" approximation.

Does iCloud photo library support any concept of date precision, where I can only set the known date parameters for a photo?

The Adjust Date and Time... feature seemingly does not allow me to delete date components or set only a certain level of date precision.

FB9370782: Allow setting less precise EXIF dates (Year + Month) for old family Photos

Solution 1:

The EXIF specification […] allows for entirely unknown dates, but doesn't have a standard for less-precise dates

https://photo.stackexchange.com/a/19685/22450

therefore the Photos app cannot support less precision in date format as it cannot be saved to the image while complying to the specification.