Krux is not a vault brand. It is AGPL firmware, funded in part by OpenSats, installed on K210 boards sold for computer vision. M5StickV, Maix Amigo, WonderMV, TZT, Embed Fire — and the Yahboom K210, now the shortest path: unbox, flash, sign.
By default nothing sleeps on the device. You can also encrypt a mnemonic in flash or on microSD: then it is no longer stateless, it is an MCU with no SE holding a secret. The choice is yours; the threat model changes with it.
Board diversity is a strength and a burden. Each board has its camera, its closed boot ROM, sometimes Wi-Fi that the Yahboom does not. Verifying the Krux binary remains the gesture, not the logo on the plastic.
Fits if
DIY firmware on K210, a leg of a multisig, budget.
Keep in mind
The binary to verify. The board is not an SE. Stateful on SD = the secret returns to the plastic.