Is spoonerism similar to dyslexia or is dyslexic in nature?
No, a spoonerism is a figure of speech. Dyslexia is a disability which impairs spelling of words correctly, for example.
An example of a spoonerism is the following :
"A well oiled bicycle" is presented as " a well-boiled icicle"
There is a shift of initial letters to produce this ludicrous phrase.
It is done for effect.