You are in good hands with an Allegiant pilot at the controls. They are highly trained, skilled professionals. Allegiant is a very competitive place to be hired as a pilot, just look down at the hiring thread at all of the pilots clamoring for a shot at and interview.
My advice, walk up and speak to the pilots on your flight. Tell them what specifically makes you nervous about flying. I’ve had many passengers do this and I think it usually helps.