Nope! Essentially all modern large thermonuclear devices are fission-fusion-fission devices, where the last fission stage (again, driven by fusion neutrons) pro

Nope! Essentially all modern large thermonuclear devices are fission-fusion-fission devices, where the last fission stage (again, driven by fusion neutrons) produces the majority of the yield. You can omit that stage, by using a non-fissile material, for easier testing (...do you really want to test a 100MT device?...) with less fallout, but in actual use, they would all have fissile tampers.