“I think that eating a fleishiks meal on Motzei Shabbos may be more than a “family tradition”. I’m not sure about this, since I never looked it up, but it may be something that really everyone one is supposed to do l’chatchila”
I think that is stretch. The Remah says Ochlim vesemachim dehavi ketzay Yom Tov” which is easy to make the case that fleishigs is preferred but it is a strecth to say “really everyone is supposed to do” soemthing that isnt brought in shulchan Aruch/Remah or Achronim.
That said Like CTL My family too has fleishigs
We also light candles motzei Yom Kippur and Every Motzei Shabbos which apparently is not a common minhag
Loweryour tuition
I liked your examples
1. Not wearing a kittel in shana rishono on Yom Kippur and Pesach.”
this isnt rare, and is quite viisble on yom kippur as many newy marrieds dont wear a kittel
3. Making Brocha on lulav and Esrog in the sukkah.
5. Eating a hard boiled egg at the Pesach Seder
These two examples are personally the opposite of the OP. They are minhagim I thought were universal as everybody I knew growing up did them. It was only later that I encountered People with different minhagim