Frankly, I'd like to see some kind of maglev-based launch platform that propels the rocket up the side of a mountain, and then lets the rocket's own boosters take over.
A device that can carry several tons to GEO and to start in a slanted position along a mountain would be a very different beast than a usual rocket.
To say nothing about building several miles of an excessively straight maglev bridge along a mountain which is likely not that straight, and also highly visible.
The problem is getting out of the thickness of the lower atmosphere. That’s why rockets go up before they go sideways.