Steroid use has been shown to increase muscle in untrained males by around 25-30% I believe, without adding any exercise. That doesn't accomplish too much. If you want any worthwhile results, you will still have to train, although the steroids produce significantly more results for the same investment.

My understanding is that anabolic steroid are somehow close to what you're thinking about? It's just that as anything taking a simple shortcut , it comes with unwanted effects

The reason no one has found a better way is because hypertrophy is because it’s well understood and there’s no “better” solution. mTOR is the primary hormone pathway.thy increase the adaptation ceiling by increasing RBC, reducing protein breakdown, etc. Thereby reducing rest needed, so mTOR is heavily unregulated.

This is one of the view places where “if we could we would” is the correct answer. There is so much money in the space of anabolic cheating, the clandestine scientists would’ve already developed it.