The severance is not for your benefit, it is for theirs. It has two purposes.
1) gets you to agree to give up any right to sue them, and
2) it lets them show remaining employees how well they’ll be treated when it’s their turn, thus helping with retention (i.e. making it more likely that Broadcom times your departure to fit their business needs).
There is no way that they would risk that to nickel-and-dime you as you leave.