If you could cryosleep, lived for millions of years, or were an AI that could just turn itself off for a while, you could go to the stars using simple chemical propulsion. No physicists’ nightmare torch rockets or warp drives required.

The crazy physics requirement is to enable interstellar flight within natural human life spans. It’s probably easier to extend that or figure out how to hibernate or become AI than it is to build an antimatter rocket or bend space time (if that is even possible).

I doubt the dark forest because Earth has been broadcasting that it’s a likely biosphere via its albedo absorption spectrum for over a billion years. If you are a hyper paranoid alien you should just blast every biosphere to kill any possible rival before it even evolves.