How to launch any activity?

Some activities are not launch-able. All activities are launch-able, but some of them may not have any effect when launched directly. They may be a window overlay, a notification, or even a simple broadcast listener.

Copying beeshyams's quotation:

An activity is the most familiar type of component: it's a window you can see: either full-screen or dialog-sized. An activity only runs while it's displayed on the screen. Once you leave the activity, Android will keep that app in memory ready to be started again, but the activity won't run, meaning it won't use battery or network. An app starts an activity using an intent. The intent can specify explicitly which activity to start, or it can specify an action to perform (such as opening a particular file). If more than one activity can "handle" the intent, you see the dialog asking you to choose one.

If you insist on attempting, you may want to explore am start command. It can start any activity supplied as arguments. Root is required in most cases.

# am start com.android.vending/com.google.android.finsky.billing.acquire.AcquireActivity

Starting: Intent {
 act=android.intent.action.MAIN cat=android.intent.category.LAUNCHER cmp=com.android.vending/com.google.android.finsky.billing.acquire.AcquireActivity 
}

Well, the above command gave no visual responses other than am's output.

You can specify another action with option -a and another category with -c, to pretend you're another app rather than a command line. However I'm not a developer, so you should work things out further on yourself.