More Half-Life: Alyx Guides:
In this guide you will find useful information about enabling the developer menu in the game.
Guide to Accessing and Using the Developer Menu
Enable the development menu
To open the developer menu (develop menu), you need to enable it. To do this, right-click on Half-Life: Alyx in the Steam library and click on “Properties”.
Then click on “set launch options”.
In the window that opens, write “-dev” without the buttons and click “Accept”.
Using the Develop Menu
To use the development menu, start Half-Life: Alyx and lock a saved game or start a new game. Quit the game after loading the game. You should have an option at the bottom of the pause menu called “development menu”. Select to open the upgrade menu. This is how the menu opens. It will reapply its normal tempo menu until it returns to it. To return to the predefined menu, in the development menu, select “game menu” in the lower section. Then select “next menu”. Then you return to the predefined menu.