I did not yet had a problem with notifications in Android but I also see app-only as a disadvantage. What if I have no internet but could be reachable via SMS/p

I did not yet had a problem with notifications in Android but I also see app-only as a disadvantage. What if I have no internet but could be reachable via SMS/phone? (still not that rare in Germany ;)) btw: there is an helpful Android app "missed notifications reminder" in fdroid store that re-triggers app-specific notifications if you do not view them within a minute.