Keystone bets on the visual air-gap: camera + large screen, QR for everything, battery, no USB data in the normal flow. Several chips, including SEs, fragment trust. Multi-coin is still there, which widens the firmware compared with a Coldcard, but isolation from the PC is real.
Clear signing benefits from the screen size. Policies, multisig, PSBTs are the native language. It is a desktop device more than a pocket dongle.
The counterpart is the bulk of the device, the battery (a vector for wear and, theoretically, for tampering), and an ecosystem less “one app for everything” than Ledger Live.
Fits if
Multi-coin air-gap, clear signing, isolation from the PC.
Keep in mind
Firmware larger than Bitcoin-only. Battery and form factor less discreet.