Where does “đ” come from?

đ (Serbo-Croatian) comes from Czech d, from Latin d, from Etruscan 𐌃, from Ancient Greek δ, from Phoenician 𐤃, from Egyptian 𓉿.

Ancestry of “đ”, step by step

Step	Language	Word	Meaning
1	Czech	d	It represents the phoneme /ɟ/
2	Latin	d	—
3	Etruscan	𐌃	de
4	Ancient Greek	δ	Lower case delta (δέλτα), the fourth letter of Greek alphabet. It represented in Ancient Greek a voiced dental plosive: and in modern Greek a voiced dental fricative:. It is preceded by γ and followed by ε
5	Phoenician	𐤃	dalet; daleth
6	Egyptian	𓉿	—