Multiple angular app initializers

We know that in root module provider we can set an APP_INITIALIZER that bootstrap some dependencies in the backend and then loads the first component

{
    provide: APP_INITIALIZER,
    useFactory: configLoader,
    multi: true,
    deps: [ConfigService]
}

I will load my user configs before the app starts in the above way, but I want to do somehing more, like connect websocket before my app starts.

I know that I can do in in configLoader function that I wrote, that first load configs and then connect websocket in that configLoader function, but for some reasons, I can't do that right now, so I need do in in someway like this:

{
    provide: APP_INITIALIZER,
    useFactory: [configLoader, websocketLoader],
    multi: true,
    deps: [ConfigService, WebsocketService]
}

But unfortunately, it won't work. So is there any way to load multiple app initializers?