• Windows with Steam Client
  
• PowerToys[learn.microsoft.com] for Windows
  
• a Controller for your choice e.g. XBOX controller

Once you have PowerToys installed you may use any of the tools it provides.
For this guide the "Video Conference Mute" is the only requirement.

Open it in the configuration in PowerToys settings

• set a shortcut for "Mute microphone"
  
• make sure you only have a two button combination.

This could look like the following:

• find the game in your steam library
  
• access its properties by right-click on the entry
  
• select controller entry on the left side.
  
• select "Enable Steam Input"
  
• switch on your controller
  
• click on "Controller Configurator" in the underlined text above.

In "Controller Configurator" you just opend you continue to setup the shortcut to mute and unmute by pressing a controller button!

We will setup a "long press on b-button" to mute / unmute your microphone.

• select "Official Layout for Helldivers 2 ..."
  
• click on "edit layout" right below it.
  
• choose "buttons" from the left menu
  
• "add extrax command" by clicking on the cogwheel on the right to the b-button
  
• choose "keyboard" from the input categories
  
• click the first key; in our example CTRL
  
• a new entry showed up; click on the cogwheel right to it, and change from "regular press" to "long press"
  
• "add sub command" via cogwheel and select your second key; in our example M

The final result should look like in this picture:

Now your B-Button from the controller has to tasks.

First, you dodge by regular pressing the button (press & release)
Second, you mute or unmute your microphone by long pressing the button (prreeeessss & release)

• make sure you have "open microphone" setup in Helldivers 2.
  
  
• if you want to see if your microphone is open or closed, you can use "Toolbar" settings in "PowerToys" a bit below where you setup the shortcut for mute.