No. I am talking about multi-level security [1] which allows a single piece of hardware to handle top secret and unclassified materials simultaneously via software protection. This protection is limited to software attempts to access top secret materials from the unclassified domain; hardware and physical attacks are out-of-scope.

There have been many such systems verified to be secure against state actors according to the TCSEC Orange Book Level A1 standard and the subsequent Common Criteria SKPP standard which requires both full formal proofs of security and explicitly requires the NSA to identify zero vulnerabilities during a multi-month penetration test before allowing usage in NSA and DoD systems.

[1] https://en.wikipedia.org/wiki/Multilevel_security