You're right, the gap between 13" B&W and 25" color e-readers is a bit frustrating! Currently, there aren't any widely available 13-15" color e-ink devices.
Here's what I know:
Onyx Boox: They offer 13.3" B&W devices like the Max Lumi, but no color options in that size yet.
Dasung: Their color offerings jump from 10.6" to 25.3" with the Paperlike.
E Ink: They're actively developing new color e-paper technologies, but haven't announced any specific 13-15" panels yet.
So, what are your options?
Wait If a 13-15" color e-reader is crucial, holding off for future releases might be your best bet. Both Onyx and Dasung are known for innovation, so it's not out of the question. A 13.3" B&W Onyx Boox like the Max Lumi might offer a great reading experience, or the 10.6" Dasung Paperlike could be a portable color option.
