Pairing CoinJoin with Lightning channels is one of the cleanest operational privacy models, as off-chain routing breaks on-chain graph analysis completely. When funding channels from CoinJoin outputs, make sure the channel funding transaction doesn't consolidate multiple mixed UTXOs, which reduces your anonymity set. While Wasabi with kruw.io works well for the mixing step, you can also use Ginger Wallet for automated WabiSabi mixing with a dedicated default coordinator. For closing channels, sweeping residual funds directly into cold storage addresses with dedicated labels ensures you avoid accidental address reuse across cycles.

Several active options remain for Bitcoin privacy post-zkSNACKs. If you prefer WabiSabi's batch efficiency, Ginger Wallet provides an active, ready-to-use coordinator out of the box, while Wasabi Wallet allows connecting to custom coordinators like kruw.io. For coordinator-free peer-to-peer CoinJoins, JoinMarket (or the Jam frontend) remains fully functional, though order-book liquidity is slower. If you use Samourai-style Whirlpool rounds, Ashigaru Wallet is the maintained open-source fork continuing Whirlpool mixing. Each trades off differently between liquidity speed, fee structures, and coordinator centralization.

The relay-policy distinction is useful, but the old free-transaction allowance did change. Bitcoin Core 0.15 removed the remaining coin-age-priority handling, including the free-relay options. A zero-fee transaction can still be valid under consensus; getting it relayed or selected by a miner is a separate question. So I'd separate three things here: whether a transaction is valid, whether a node relays it, and whether a miner includes it. The removal is documented here: https://bitcoincore.org/en/releases/0.15.0/.

I'd add three separate risks to that cost/risk/complexity comparison: exposing your purchase details, losing signing keys, and linking your on-chain activity. The shipping-provider leak concerns the first; it doesn't by itself reveal a wallet balance. Generic hardware may reduce one purchasing trail, but key storage and recovery still need testing. Multisig changes the key-compromise risk and adds backup complexity. It doesn't remove an address from a shipping database.

Bitkey's https://support.bitkey.world/hc/en-us/articles/41831614173460-What-is-the-private-wallet-update answers this more specifically: when its server co-signs, it can temporarily see the wallet balance, not just the payment you're making. Bitkey says it doesn't log that balance. Chain code delegation limits ongoing address derivation by the server, but 'doesn't retain it' and 'cannot see it' are different privacy claims. I'd compare those exact cases with each assisted-recovery provider's documentation.

The automation doesn't require custody. Ginger and Wasabi already show that coinjoin can run in a wallet where the user keeps the keys. For the game idea, I'd make the spending budget and who pays mining or liquidity fees explicit. An app can hide protocol names from the main flow; it should still make clear who controls the coins and what each action authorizes.

SeedSigner isn't listed in this preview. The release notes list Trezor, Coldcard, Passport Prime and Krux, with specific firmware or setup requirements for the latter three. PSBT support alone doesn't establish compatibility with this coinjoin workflow. This is an unofficial experimental Wasabi build, so I'd treat SeedSigner support as unconfirmed until the author documents it.