If an attacker controls your laptop at the moment you unlock your key, they get whatever you can read. No secrets manager of any design prevents this. Hardware custody raises the bar considerably, since the attacker has to be present and active at the moment you touch the device rather than quietly copying a file at their leisure, but it does not eliminate it.
Practical consequences: keep the client's key cache short, prefer secretsmgr run over writing .env files, and treat a compromised developer machine as a full credential-rotation event, not just a re-imaging job.