Green’s Dictionary of Slang

nothing at all.

1981		G.V. Higgins Rat on Fire (1982) 90: Just a kid that didn’t know shit-all from what he was doing.
1995		Guardian Weekend 1 July 20/3: The lads thought ‘we’ve got shite-all’.
2001		(con. 1964–8) J. Ellroy Cold Six Thousand 174: The Sheriff’s man knew shit-all about it.
2012		M. Lacher On the Bro’d 74: Ricky had taken my workout video idea to LA [...] and shit-all happened.
2022		I. Fitzgerald Dirtbag, Massachusetts 53: [W]e didn’t have shit-all else to do.