It depends on whether your heirs could reconstruct what you built, together, after you. One device and one seed is a plan that is tested exactly once, and at this size a single lost seed or one coerced evening is total loss. The exposure ceiling flags that whatever else the setup scores. The models that remove the single point of failure without asking three people to run a signing ceremony are multi-institution custody and, where a technical heir exists, collaborative multisig with a documented inheritance service. Selling into an ETF is a taxable sale and swaps key risk for issuer and custodian concentration; it is a trade-off, not an answer.
Fit engine rules 0.1 (1 Nov 2026), with this situation's inputs preset. Adjust the inputs to your own case. Proof of Custody is published by Onramp Bitcoin, which appears here where its custody model fits and is scored by the same methodology as every other platform.
Recovery: Identity and authority documents to the institutions; no device, seed or ceremony on the heir's side.
Single point of failure at this size: one device, company or person can lose the whole holding.
Recovery: Identity and authority documents to the custodian; the custodian's own succession procedure.
Fits only where the provider documents an assisted inheritance path the recoverer can follow with support; otherwise the arrangement becomes a puzzle box the day you are gone.
Recovery: Locate the devices and seed backups, run a signing ceremony with the provider's key; or, where the provider documents an assisted inheritance path, follow that path with the provider.
Single point of failure at this size: one device, company or person can lose the whole holding.
Recovery: Prove identity and, for an estate, present letters of administration to the company's support desk.
Single point of failure at this size: one device, company or person can lose the whole holding.
Recovery: The brokerage's beneficiary or estate process; no keys involved.
Excluded by the rules: Self-managed multi-vendor multisig (Recovery floor: this model requires the recoverer to run a hardware wallet and handle a seed phrase, and the person you named cannot be expected to.); Single-signature hardware wallet (Recovery floor: this model requires the recoverer to run a hardware wallet and handle a seed phrase, and the person you named cannot be expected to.)
These are custody models that fit the situation described, by Proof of Custody's published rules, version 0.1 (1 Nov 2026). They are not a recommendation to buy, sell, move or hold anything, and not legal, tax or estate advice.
The buyer will not store a device, will not write down a seed phrase, and will not be responsible for anything physical.
The buyer holds more than $10M and needs the arrangement to survive scrutiny from a board, an auditor and an insurer.
Agent tool: fit_custody_setup. Primary sources: poc-scores, poc-hardware. Refresh: rules versioned. All routes.
Free, read-only, no key. Every answer carries its source URL, as-of date and the publisher disclosure.