Right now there are a LOT of retirements looming at the big three.

Enlisted active duty service to earn GI Bill would normally be a fine idea, personal growth and avoid debt.

But frankly you would miss much or most of the coming retirements. Depending on pilot demograhics and the economy the airline industry can be very stagnant for very long stretches. Given that, I would try to get on with it faster, one way or the other. Guard (or USAFR) while attending college would be a good idea especially if you can get a pilot slot once you get a degree.

Having an avionics or other maintenance background will not make you more competitive for airlines. Their criteria for pilots don't really include maintenance experience.