Orange has created such a font, named Accessible-DfA, and made it available as an Open Source ressource.
There is a need to improve the legibility of written information. This is particularly so for low readers but also for frequent use, and finally for everybody that want a legible interface.
It may be for persons with visual impairment, (low vision user, cataract), for low literate user, for learning reader, hard of hearing user using efficient subtitling, and all user facing reading difficulties (as dyslexia), or due to contextual constraints (as outdoor use of a mobile phone, or car driving interface).
A smart font has open and large characters, quite different one from the other, easily perceptible, with reinforced diacritics and punctuation marks.