Reason I ask as someone was using their A7iii last night to capture fireworks and only had a 35mm lens which I thought was strange.
When I asked, their response was they only had the budget for a 35mm.
To be fair then that would exclude the 100-400GM
You asked the wrong question. If you ask which lens you couldnt live without and be the only lens you have you will get comments like the 24-70GM, some of the primes etc.
Asking what your first lens should be will get you a different answer.
Personally a 35mm or 24mm prime is a very sensible first lens to own.