How do I cope with being stuck between sales and engineering?

You can run a demo that closes the deal on its own, and you are tired of living in the gap between two teams that each treat you as the other's. Sales thinks you are engineering, engineering thinks you are sales, and you belong fully to neither. That is a lonely place, and the loneliness is real even though the skill is rare. Try to reframe the position you are in. Living between two teams is not homelessness. It is a bridge, and bridges are valuable precisely because they touch both sides and belong wholly to neither. The very thing that makes you feel unclaimed is what makes you able to do what neither team can do alone. Still, you need a place that feels like yours, so build it deliberately. Find the others who live in this in between role, even in other companies, and make them your people. And get clear with yourself about the worth of what you do, so you do not need either team to claim you to feel solid. You are not caught between two worlds. You are the one who can move through both, and that is a strong place to stand once you stop waiting to be adopted.