Annotating the profile photo's definitely a good idea - I already add text to the profile images to identify anybody who died as a child, or anybody whose connection/details are not based on my own research.
But I can't think of a simple way to indicate on a profile photo that a person was married twice with no children after having had an illegitimate child with a different person. To me that's something that would be better indicated by (or on) the line joining the couple.
Maybe I am being very stupid, but what is the advantage, please? Ancestry allows me to make prodigious notes on any relationship. My cousin was very promiscuous, one of her one-day partners and the father of her 5th child was "Unknown rugby player, Clifton College First XI". How that would translate into an emoji, I don't know.
Regards
Chas