Design for sound-off first
Assume the first play is silent. The voiceover's job is to reward the person who taps the speaker, not to carry the message alone. Keep it to two to four sentences: the hook, the one thing to know, and what to do. Everything else belongs in on-screen text. Because the script is short, generate two or three variants with different voices and pick by feel — each generation takes a few seconds and there is no cap.