No option to turn on Wii Balance Board on Dolphin RetroArch core

[MichaelAceAnderson]

Game Name
Wii Fit Plus (Europe)

Game ID
RFPP01 (0001000452465050)

Problem
There is no option to turn on the Balance Board on the Dolphin RetroArch core
(Quick Menu > Input, only options regarding Wiimotes, nothing about Balance Boards)
I have to manually add this to the config (User/Config/WiimoteNew.ini)

[BalanceBoard]
Device = DInput/0/Keyboard Mouse
Source = 2

Expected behavior
There should be a toggle somewhere in the core/input options just like the tickbox on regular Dolphin standalone emulator, in order to add an entry in the config that allows Balance Board detection

Steps to reproduce the bug
Launch Wii Fit Plus or any game requiring a Balance Board, go to Quick Menu > Input, find only options regarding Wiimotes, nothing about Balance Boards

Technical informations
Version: Retroarch v1.21.0 - dolphin-emu (a09f78f)
CPU: AMD Ryzen 7 3800X 8-Core, 3.9GHz
GPU: NVidia GeForce RTX 3070
OS: Windows 10