To the OP
If the owners thought you were vital, they would not put you in a situation where you’re looking for a new employment. One way or another they would communicate to you how important you are to the operation. If that hasn’t happened, you are probably not vital in their opinion.
I had an employer that I informed I would be starting to look for a new position, and why, and they should start looking for / training up my replacement. A few months later I found the right place to move to, and put in my notice. It was at that point they took notice and told me how important I was and how hard to replace. I said "If I was that important, why didn't you address any of my concerns?"
Moving was the best thing I could have done, and put me in a much better position.