I'm looking for fics that have strong focus on wizarding culture, customs, and heritage.

The kinds of stories where Samhain and Yule are celebrated instead of their muggle equivalents Halloween and Christmas, etc. Where they have their own beliefs and traditions.

 

Well, the Sacrifices arc would be the obvious pick, but that comes with the usual warnings of heavy angst, slash, etc. (Excellent if you can tolerate those, otherwise skip.)

A Necessary Gift: A Harry Potter Story is ok.

Prince of a Dark Kingdom, in a certain way, I guess.

 

Have you read Untitled Tome, Cyclops? My memory of it ist hat it has the sort of intricate and unique worldbuilding that brings with it a focus on wizarding culture and customs.

 

I'm always quick to recommend On the Wings of a Phoenix for something involving wizarding culture and heritage. It's a bit rough in spots (such as anything involving Ginny) but there's a lot of great concepts in the story that make it probably my favorite bad story.

 

Anything by Taure probably fits the bill.

Can't recall how much mira mirth goes into it, but Slytherin!Harry as a general rule leans this way. Although YMMV, quality-wise.

 

The only fics I know that do this well Malachite Path and Professor Riddle and the Quest for Tenure

 

Besides A Necessary Gift which has already been mentioned, the first story I read that celebrated such holidays was Beltane Child:
https://m.fanfiction.net/s/9415372/1/Beltane-Child