Just took a bit of scrolling through UnicodePad. I knew it would likely not be in the Basic Multilingual Plane (U+0000~U+FFFF) because QaZ didn't have it so I just scrolled from the end (skimming past obviously irrelevant blocks like emoji, music or too curly) and found U+11ABD 𑪽: CANADIAN SYLLABICS SPI in the Unified Canadian Aboriginal Syllabics-Extended A block. Another option is the Insert Symbol function in Google Docs, which recognizes Unicode characters by a shape you draw, but it's been around for 10+ years and seems to not have been updated to include 𑪽.
Oddly enough, the normal Z-shape is present in various scripts (𐌶𐔇𐨚𑢩𑪼𑫑ꮓⲌᮔᏃ႗ჍΖ) and so is the И-shape, but their mirror images are way less common. Perhaps it is more natural for right-handed people to draw / diagonals than \.
