Al-Haitham is an upcoming 5-character and will play a significant role in the main Sumeru storyline, per leaks. Additionally, Dehya and Nilou will be introduced through the main story itself.

Current leaks don't mention Al-Haitham being playable in Genshin Impact 3.0, so Travelers will likely have to wait until 3.1 or later if they plan to summon him (his specific release date is unknown).

Genshin Impact: Al-Haitham, Dehya, Nilou, Nahida & Cyno Shown in Trailer, More Info on Sumeru City. New trailer offers first looks at upcoming characters, Sumeru, and its lore. + ...