How to display unicode characters or add extra fonts?

[Former user]

I would like to display unicode characters in equations, e.g

\unicode{26A1} (High voltage symbol : ⚡)

As an alternative I would like to include a Latex symbol, e.g. \faFlash

=>How can I do so? => Is it possible to contribute to the preamble to include some additional fonts?

[Scott Selberg]

I'm not sure either.