I would say a paper wallet made to be fireprrof, waterproof etc. Would be a great way. Your relavites/loved ones could figure out enough about crypto without messing anything up. It is not unreasonable to think that a non crypto savvy person would mess up with a a hardware wallet or app.
You can see some reccoemndations here: https://blog.lopp.net/metal-bitcoin-seed-storage-stress-test--part-ii-/
Have gone through the link mentioned in the answer.
I am amazed that such devices exist, thanks for sharing the information.
I am going to do some research on the topic and then only form an opinion.
Best of Luck!