The Keyboard Shift Cipher
Jelly, 13 bytes

ØQØDṭ,ṙ€¥⁸F€y


Try it online!

How it works

ØQØDṭ,ṙ€¥⁸F€y  Main link. Left argument: n (integer). Right argument: s (string)

ØQ             Qwerty; set the return value to
               ["QWERTYUIOP", "ASDFGHJKL", "ZXCVBNM"].
  ØD           Digits; yield "0123456789".
    ṭ          Tack, yielding ["QWERTYUIOP", "ASDFGHJKL", "ZXCVBNM", "0123456789"].
        ¥⁸     Call the two links to the left as a dyadic chain, with right
               argument n.
      ṙ€       Rotate each string in the array n units to the left.
     ,         Yield the pair of the unmodified and the rotated string array.
          F€   Flatten each, mapping, e.g., ["QWERTYUIOP", ..., "0123456789"] to
               "QWERTYUIOPASDFGHJKLZXCVBNM0123456789".
            y  Translate s according to the mapping we've built.