Don't just look at the equipment cost itself. Almost anything is going to have a monthly fee associated.
There may still be wrist devices sold that "tether" to a phone, but if you want fall detection or "press for help" you'll probably need a full-blown "phone watch." Otherwise you need a specialty device bundled with a dedicated monthly fee.
So a fee-based dedicated service or (additional?) cell phone agreement/2nd device add-on.
I don't know much more, maybe somebody has actual experience? It
does sound like Samsung, Apple, Google Pixel might be the top brands to research though.
But things like this exist as well: