Given what OP describes

> Our biggest pain point with hosting agents was that you'd need to stitch together multiple pieces: packaging your agent, running it in a sandbox, streaming messages back to users, persisting state across turns, and managing getting files to and from the agent workspace.

The k8s ecosystem already handles most this and your agent framework the agent specifics. What you are talking about is valid, though a different axis imo. Quality and guardrails are important, but not discussed by OP.