AFAIK, having a space should work fine. Eg. # 2 is not a tag. It is only a heading if it is the first thing on a line.
What you are requesting is what is usually called “escaping”. Indeed, we want to do that. Something like the backslash, though the exact syntax/approach hasn’t been decided. It would allow you to escape any special meaning that the characters had.
For now, we have a primitive form of escaping. You can make any text “fixed-width” format, or any paragraph, “preformatted” format. Both of these will prevent the markdown being applied.
eg of apps using # for tags: