Does baited hook kill friendly unit part of finalization or resolution

Resolution. Baited Hook's kill is part of the ability's effect, so it happens when the ability resolves — not during finalization.

Its cost is only [1][C] plus exhausting [E]; "Kill a friendly unit" sits in the effect text and executes top-to-bottom at resolution (Rule 158.1). What happens at finalization is only the choose/target step — you pick which friendly unit to kill when the ability is placed on the chain, which is why opponents get a Reaction window before the kill actually occurs.

Practically: if the chosen unit is removed or bounced in response, nothing gets killed, the "killed unit" reference is null, and you look at 5 cards but can't play any of them. The kill instruction does create the pending Deathknell trigger before the unit hits the trash (Rule 428.1.a.1.b), and per LIFO that trigger resolves after the rest of Baited Hook finishes.