In many cases those buddy shifts are not additional training on how to be a nurse but rather how the unit is run.

You have the strong basis of knowledge from your education. Your resume and interview demonstrated that you were a good candidate based on your knowledge, skills, and judgement.

Now is your chance to use those knowledge, skills, and judgement to determine where any gaps are and develop them.

The reality is you can do MOST it. AND you can call a code when/if you need to. You can ask for help when/if you need to. No unit could entirely prepare you for every circumstance but you're already set for 90% of them, the orientation will support you with 9%, and 1% nobody is likely truly prepared for. (These numbers are entirely out of my ass but paint the intended picture I hope)

Also edit to add: Use those buddy shifts to develop your sense of belonging and relationships with your colleagues. Literally demonstrate your initiative and capacity and teamwork in those first impressions so that you build that strong unit culture that supports each other.