

In smoke detectors and tritium watches the quantity of radioactive material is minuscule compared to the beta emitter in the battery, as in multiple orders of magnitude less. None of the things you mentioned have radioactive material in any significant quantity. If you swallowed or inhaled this battery you’d be exposed to significant amounts of radiation.
A microwave is not an ionizing radiation source.
“Drinking hot tea is safe so drinking boiling water, which is also hot, should also be safe”
The quantity of radioactive material and what form of radiation it emits is extremely relevant to this discussion.
We have seen nuclear batteries - it’s decades old technology at this point. They were used in pacemakers. They stopped in the 80s because it’s too expensive and dangerous. You have to track radiation sources like this.