Daylight computer screen is the best.

Epaper is has poor latency, and cannot be used in daylight.

There is quite a wide range of e-ink devices now, but the software is often janky. For ebooks there is also the format/store question. Does she buy her books on Amazon? If so, a Kindle Scribe might be a good bet. But it's locked into the Amazon ecosystem. I highly recommend clearly identifying the main use case, then shopping based on that.