Kidding aside, it depends how easy it is to make allies and factions in HOI4 as compared to HOI3. In HOI3 you'd be doomed. But in HOI4, if its possible for you to set up an alliance strong enough to resist Germany you'd probably be in a fine position going forward.
Annexation will never be automatic if you play Austria you'd have a choice, and by resisting it means you'd be at war with Germany. To survive as Austria you'd need allies and to get ready for war starting day 1 making the right preparation choices.
if you ally italy it tends to work where they come to help you although it kinda breaks the game because germany is so interested in you that soviets just take over everything later when the allies go to war vs them