This puts atomic bombs behind Aquilo and even further back, because also these packs are needed, and that's perhaps a bit too much?

It would help me judge the technology cost if you describe how you use atomic bombs in a regular Space Age game.

In vanilla space age, it is unlocked with only Nauvis science and space science. I think that is fine, so you can still use it before the game is "over"

In my experience, the game involves colonization of all the planets and then expansion. Clearing a lot of land is useful for expansion to get high weapon damage bonuses, which are needed to approach the shattered planet. I can remove the dependence on advanced research, so that you only need lithium as an ingredient and you don't need to expand on Aquilo.