Are you looking for people who play in the style of West Virginian Frank Hutchison i.e slide guitar? or are you looking for Piedmont Blues men such as Blind Boy Fuller? Two different styles.
If you are looking for slide guitar players from the white tradition you could try The Dixon Brothers, North Carolina mill workers one of whom played slide or Darby & Tarleton. Jimmie Tarleton was "rediscovered" in later years and made a solo album accompanying himself on slide guitar

Hoot