>>510724419
>>510725563
All important software –including Microsoft Office and the Android keyboard– include the extra dashes and substitute for them when the user types '--' or '---'.

Other marks like '…' and «» are easy to find as well —even if they're not printed on the keyboard physically. You can get way more by configuring your layout properly too like in pic related.

This entire thing was written with the default Android keyboard, by the way.