Having everything written down can make it easier, particularly if she is not familiar with the Apple world. You can also provide links to key Apple support articles which will have the step-by-step instructions. She can, in fact, gain access to some of your account items as outlined in How to request access to a deceased family member’s Apple Account - Apple Support Note that it says "court order" and I don't know if there's a way to do a shortcut since not all estates have to undergo probate. Maybe speak with your lawyer. Of course the easiest way to avoid all that is for you to make a note (and keep updated) of your account user ID (Apple ID) and password. Of course then it's a matter of keeping it secure and private until she needs it. Again, a way to avoid all that is --> How to add a Legacy Contact for your Apple Account - Apple Support . A Legacy Contact’s access to your Apple Account is limited as described in Request access to an Apple Account as a Legacy Contact - Apple Support .
If you have your receipt for your Apple equipment from an Apple authorized dealer or Apple itself, keep it in a safe place. Should it be necessary it would allow her to ask Apple to reset your equipment. This would only be necessary if she did not have access to your account.
https://al-support.apple.com/#/additional-support
If she can get access to your accounts, she may also wish to know about What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support