When it comes to bitcoin inheritance planning, don't give your heirs too much credit.
I've helped with 100s, if not 1000s, of probates (the process for transferring assets and settling debts upon death), and this is what we see:
Over and over we see heirs fumble and struggle with even legacy assets that most people are familiar with (bank, brokerages, and annuity accounts).
Probably due to some combination of grief, time constraints, and the stress of handling someone else's personal affairs on top of your own busy ilfe.
So it's hard to imagine a non-Bitcoiner, in these circumstances, successfully figuring out a hardware wallet or utxo, let alone anything more esoteric things like a sharded seed phrase or multisig vault. It just doesn't seem realistic.
If you still believe you're Shakespeare and can write that perfect letter of instruction, try this mental exercise:
Imagine your uncle says he will leave you his substantial wealth, but it's all located in a completely foreign and corrupt land. Maybe even some alien society run by the Hutts, whatever.
You don't know the basic language, let alone the slang or technical jargon. Their notions of how value/wealth is stored are completely different from what you're used to. You have no understanding of the legal system (to the extent any laws exist), or local systems or customs. Oh, and everyone there is trying to screw or rob you, and if you mess up the wealth is irrevocably stolen or lost forever.
But no worries! Your uncle promises he'l write a really good letter, so nbd right? It took him years of self-study to (sort of) confidently navigate that environment, but his letter is just as good, right?
My theory: the "correct" bitcoin inheritance solution will be different for everyone. But unless your heirs or executor are deep down this rabbit hole, please don't assume you can write the perfect letter of instruction or design the "simplest" treasure map that will guide them flawlessly to safe self-custody.
Appreciate any and all feedback