Alternatively, can you write the character by strokes (that the pinyin input recognizes it and that the character can be found among all the other stored characters)?
Although the character cannot currently be typed into a computer, wikipedia notes that one may use a phonetic substitution. I doubt that most people would recognise this 58 stroke original character in any case but at least this may be a usable substitute.
The Chinese character for "biáng" cannot be entered into computers. Therefore phonetic substitutes like Chinese: 彪彪面; pinyin: biāobiāo miàn) or Chinese: 冰冰面; pinyin: bīngbīng miàn) are often used.
(Wikipedia, n.d., https://en.wikipedia.org/wiki/Biángbiáng_noodles#Mnemonics)
Now Unicode has just supported it. Click http://www.unicode.org/versions/Unicode13.0.0/, In detail, you can check this document https://www.unicode.org/charts/PDF/Unicode-13.0/U130-30000.pdf.