Where does this style work?

It works wherever plain text is accepted — bios, usernames and comments — because the letters are real Unicode characters, not a font.

Can I copy it together with other words?

Yes — copy the whole output and paste it next to plain text; every letter stands alone.

Blackboard bold — math and aesthetics

Double-struck (blackboard bold) letters (𝔸-𝕫, 𝟘-𝟡) come from mathematical set notation — the academic aesthetic for bio headers.

𝕐𝕠𝕦𝕣 𝕥𝕖𝕩𝕥 𝕙𝕖𝕣𝕖