What do I do if I wanted everything and all accounts deleted immediately upon the event of my death?

Specific instructions as to the disposition of your digital assets should also be explicitly included in your will.

If possible, it would be helpful if your designated executor was a legacy contact.

You can add a legacy contact and ask them to remove your account inmeadeately after your death

See this link on how to do that

How to add a Legacy Contact for your Apple ID - Apple Support

Apple does not provide a “dead man’s switch” mechanism.

You’d have to design, implement and test that yourself.

Or retain a lawyer or maybe executor and the legacy contact mechanism, as mentioned above.

Or by default, if nobody has your (robust) Apple ID password, then nobody can get at that data.