If that’s the purpose of a signing device, I’ll still take the added bonus of a device that can provide security when physical access is compromised.
Discussion
Security is measured in time. That is, the time it takes a knowledgeable attacker with the right tools and physical access to break in.
The best physical safes have time ratings on the order of tens of minutes. A TL-30 can withstand 30 minutes of attack, costs thousands of dollars, must be bolted to the floor, weigh 600+ pounds, and is considered top of the line by retail standards.
Expecting more than a few minutes of resistance against a knowledgeable attacker with the right tools and physical access is unrealistic. Especially considering that your attackers can be improving their techniques while your material is at rest.