If they’re considering optical media, typical BD-R, while viable, may not be be the best choice. BD-R M-Discs would probably be a better choice for backups. Especially if they’re planning on needing access to the data over a period of decades, which would be potentially useful for familiy photos/videos and critical documents.
They are more expensive, as is the drive needed for them, but not by enough to be out of reach or even unreasonable given the additional durability of the discs.
A couple of years ago I lived in a house with a few friends that we rented from one of their parents. They had a somewhat extensive homeassistant setup. We set up a couple of fun automations.
-Enter 8675309 on a keypad by the door - Play the song at full volume
-Enter 911 - Play police sirens at gradually increasing volume
-Enter 420 - Play that one sample of Snoop Dogg saying “smoke weed every day.”
-Leave the fridge or freezer door open for more than five minutes, start playing Dare to be Stupid by Weird Al at full volume and set all of the lights to red.