Do your plugins/products work with Divi 4.0 (Theme Builder)?
The Mobile Menu Customizer and Desktop Menu Customizer plugins both are fully compatible with Divi 4.0 but both of these plugins support the native header of Divi theme, they do not support the Menu Module and the Fullwidth Menu Module which are used to create headers with Divi Theme Builder.
The Theme Builder header removes the native header from every post/page it is assigned to (you can have either one or the other on the same post/page), so, if you assign a Global theme builder header on your site then you won't be able to use neither MMC nor DMC plugin because the native header will be removed from the entire site.
But if you want to create theme builder headers for specific posts/pages only, then you can use the MMC and DMC plugins to customize the native header where it is still being used(on posts/pages that haven't been assigned a theme builder header).
All other products(plugins/modules/layouts) are fully compatible with the Divi 4.0.