Speech to text device

Hi, does anyone know of a small device, handheld, for speech to text. I’m not looking for a mobile phone.

But something small, where you say one word, and the device shows the world in large font. Device not connected to WiFi, or other extra stuff.

As a study aid for a young dyslexic child.

Or maybe someone has tips how I can build this myself for example raspberry pie or something?

We have speech to text on IPad for homework, but it’s to large to keep in the pocket. Also a reading pen, but it does not have this option.

Preferable the size of the old fashioned beepers.

All tips welcome in the hope I find a solution quickly :)