Just got this question closed at SuperUser, so I hope I'll have more luck here.
I'm trying to help some elderly relatives, that cannot hear nor remember well.
They had remembered that at a certain point, they had used something that was a wireless device, that could beep extremely loud and vibrate at the same time in order to alarm/notify the user - and they would like something like that to set time duration based reminders/alarms (for instance, one would be able to set: "beep in 30 minutes"; or "beep in 2 hours").
The only thing this kind of description reminds me of, are so-called "restaurant pager coasters" or "buzzer" systems; as an example here is an image from https://www.jiantaotech.com/collection/wireless-guest-paging-system, for a product called "JT-9301 Coaster Pager Restaurant Paging System"
Obviously, the use case of these is different from a single-person use, so you're usually sold a set of "bricks"/"coasters", and a simple "remote control" to trigger them.
What I would need instead, is a single such "brick"/"coaster" that can beep/ring extremely loud, flash lights and vibrate - but would either have some simple interface on-device, to set a timer (to beep in some time, say 15 mins or half an hour) - or be controlled via smartphone (preferably Android) app: e.g. the app helps you set the timer alarm (when the device should beep), or cancel a running timer/alarm, either over Wi-Fi or over Bluetooth.
My biggest problem is - I have no idea how such a device would be called/named, so I cannot really find anything useful; all I find are restaurant pager systems like above, which I cannot really use as a settable alarm widget for an elderly person. Would anyone have an idea about what terms I should search for?