“One should not point out or make it obvious that Harchakos are not being held of at the time, as it is a lack of Tznius”
I was told in chasan classes that the tznius issue is NOT whether your wife is now a nidda, but which night she is going to the mikva. I was told there is nothing wrong with being or not being a nida, and it is not untznius if others know. After all, if you pass your wife the keys, it is obvious she is not a nidda, and if you put the baby down on the sidewalk, it is obvious that she is a nida. Unless someone is watching and making a mental note each day to see when I start handing her the keys directly, people will not know when she went to the mikva, and this no breach of tznius. (And if people are actually doing that, then I think that THEY have a problem.) I have never heard that one needs to (or even should) keep harchokos in public at all times.
Regarding actual displays of affection with one’s spouse (e.g. hand-holding), I would love to see a source. It seems to me to be slightly distateful, but not such an outrageous display or pritzus that it needs to be reprimanded, but that seems to me to be a societal issue, and would probably be different depending on one’s community.
Regarding displays of affection with one’s child (other than in shul, as mentioned above), I would think (hope) that, especially with the obvious difference in age, anyone who sees such a display by a frum person would be dan l’chaf z’chus that it is the child, and not suspect one of inappropriate conduct, but again, this could differ by community.
Finally, the OP requested sources, and none have been given, so it seems to me that all posts (inculding mine!) are personal conjecture based on each person’s feelings and/or community standards and not halachic. Still waiting to see sources!