To teach phonics I would recommend using traditional methods, such as working with the learner to directly sound out and then repeat words together to form "routine" words to build basic vocabulary and then, perhaps, improve phonic processing by creating "nonsense" words or syllables (such as "s-w-ar", "l-ox" etc.). In the digital world, there are is a vast array of resources out there for parents and teachers to work at this level.
One of the main hurdles will be finding a suitable structure by which to create and build phonic awareness. If supporting English awareness, good resources come from BBC Bitesize (www.bbc.co.uk/bitesize). Resources used to teach TEFL may be adult themed but with a bit of creativity they can be adapted to work with all ages.
Many parts of the brain's skillset are employed and developed whilst language awareness is built, so it is my belief that learners are unlikely to thrive unless the combination of attention regulation, physical (being shown, carrying out and experimentation) and sensory processing opportunities available in traditional learning settings are offered.