Fizz-Buzzify a String
Charcoal, 26 24 bytes

ＦθＦ⎇﹪℅ι²buzz¦fizz⎇№αι↥κκ


Try it online! Originally inspired by @CarlosAlejo. Edit: Saved 2 bytes by looping over the letters of fizz/buzz instead of assigning to a temporary. Explanation:

Ｆθ          Loop over the input (i = loop variable)
  Ｆ         Choose and loop over the word (k = loop variable)
   ⎇        Ternary
    ﹪℅ι²    If i has an odd ASCII code
    buzz
    fizz
            Print (implicit)
  ⎇         Ternary
   №αι      If i is an uppercase letter
    ↥κ      Uppercase(k)
     κ      k