This really sounds like a _you_ problem and not something you need hardware to fix.

You can already enable silence/focus time bypass modes for apps like PagerDuty and such…

If you can’t develop some sense of responsibility to check if you’re on-call, frankly you have no business being in an on-call role.

No hardware will make you or your engineers more diligent. The only reason pagers made more sense than phones is/was because of protocol reasons NOT because it’s some separate device.