Critiques of Trinitarianism from Jewish and Muslim perspectives tend to be clear, incisive, and damning if you don't already accept Christian priors.
I am aware that neither of those religions agree with a literal trinity. The Trinity is certainly one idea that unites Protestants and Roman Catholics.
Perhaps it is a good criterion to separate Orthodox and heterodox Christians.
I am not all that familiar with specific non Christians who criticized the Trinity doctrine, and it doesn't seem be of great interest to non Christians.
I doubt many here have read
https://en.m.wikipedia.org/wiki/The_Adventures_of_the_Black_Girl_in_Her_Search_for_GodI would recommend it; it's not specifically aimed at orthodoxy but rather religion in general.
Christian "literalism" does not imply to me the idea that everything is to be taken literally but rather an Orthodox view of theology.