I’m a bit ambivalent: I would have hated it, and there’s no immediate benefit. I’m also well past the point of being affected, so yes, you should have compulsory service.
Compulsory service can’t create an effective military force, but what it can do is widespread experience with discipline, working together, basic weapons familiarity. There are many emergencies where having this widespread experience might be useful, over a herd of random citizens in an unruly mob. Heck, make it part of national guard or have fema run it.
For the military, you might get a head start on getting people ready, should you ever have to call them up. In recent decades we always assumed war is fast and you can only use what you start with, but Ukraine demonstrate there can still be protracted wars.
But I’m picturing more of an organized force to help in a large flood or fire for example. Or it helps to have some sort of goal, so build it as a modern WPA.