The three things you found are genuinely different and only one of them is shadowing.
Shadowing is speaking along with audio at a delay of about a second, continuously, without stopping and without a transcript in front of you. You are not repeating after, you are speaking while listening, which is what makes it hard and what makes it work.
Listen and repeat is a different exercise, and a fine one. Easier, and it trains something else.
Reading aloud along with audio is a third thing, sometimes called parallel reading. Useful, and much easier because your eyes are doing the work your ears should be doing.
What shadowing actually trains, and this is the part nobody says: it is largely a motor skill and a perception exercise, not a comprehension one. Because you have no time to think, you cannot translate, and you are forced to reproduce the rhythm, stress and connected speech of the original directly. That is why it helps pronunciation and flow specifically.
Which makes it well suited to your problem. Your listening is fine and your mouth is not - that is exactly the gap it addresses.
What it will not do is give you things to say. It builds the delivery, not the content, and people who shadow for months and still cannot hold a conversation have usually done only this.