With WoTLK and up you are able to use an addon called ConsolePort which allows you to play with a controller or with a handheld device like the ROG Ally/Ally X, Xbox Ally, Xbox Ally X, Steam Deck and more. to download you just go to Download Client and download Console Port and if you are on windows, Download WoWMapper.

How to use?

Windows:

1. Download Client from here

2. Install client

3. Download Console Port here and WoWMapper here.

4. extract Console Port to Interface\AddOns 

5. Extract WoWMapper and run.

6. Log in and set up.

SteamOS:

1. Go to desktop mode
2. Download Client from here
3. Install client
4. Download Console Port here.
5. extract Console Port to Interface\AddOns
6. add wow.exe to steam
7. return to game mode
8. go to wow.exe and bring up the controller config in game mode
9. set up with the following settings:
   
   Steam deck key bindings:
   DPAD ⬆️ = F1 DPAD ⬇️ = F3 DPAD ⬅️ = F4 DPAD ➡️ = F2
   Left stick: ⬆️ = W ⬇️ = S ⬅️ = A ➡️ = D L3 = Left Mouse Button
   Right Stick: Joystick mouse R3 = Right Mouse Button
   Face Buttons : A = F11 B = F10 X = F12 Y = F9
   Triggers : L1 = CTRL L2 = SHIFT R1 = F7 R2 = F8
   START = F6 SELECT = F5