If you don’t mind a bit of work, you could look into one of the DIY smart watches on hackaday or whatever. Since you don’t need a watch form factor, that should

If you don’t mind a bit of work, you could look into one of the DIY smart watches on hackaday or whatever. Since you don’t need a watch form factor, that should give you a little extra room in terms of size or components. I found them a little too bulky as a watch for my taste, but they might work as a pager-like device.