Cyanide Pill: Played straight in the past, although the old-style cyanide pill was replaced when possible with direct kill-switch brain implants, thought-triggered, such that it was a lot harder to stop someone from using one.

Subverted in the modern day – since while the power source for the bug-out transmitter can be and often is a tiny one-shot antimatter generator that will generate enough heat to thoroughly denature, if not boil or vaporize, the users’ brain (if not the room they’re in, antimatter grenade style, or indeed more – the military model can hold up to 1 mg of antimatter, which would create an explosion roughly equal to 42 tons of TNT, although a load this heavy would be… highly unusual outside very aggressive negotiations, etc., due to the collateral risk; micrograms are more common), their mind-state is transmitted back to home base over one channel or another first for later reinstantiation.  Thus, not exactly a suicide pill.