I think handgun training ought to be the priority for non-MIL, including LEO, because it’s our primary and frequently only weapon, and because it’s simply harder to use well than a long gun.
The biggest training gap I see is very close quarters or entangled fighting. Frankly, unless you are planning to be attacked by an IPSC cardboard target at 10 yards, this is something to plan for. Desired learning objectives: when NOT to draw the handgun, how to avoid having it ripped away/stolen, how to create time and space to draw (most people have around a 2 second draw…that’s a long time in a grappling fight), how to draw and shoot from retention, etc. The reality is that an aggressor might close in on you rapidly but still not meet criteria for lethal self defense until they get to contact distance where they then attack.
The above paragraph is also directed at me, I have shot from retention at a class but need close quarters combatives/contested draw training.
Unfortunately this is always an advanced training course that (rightly) shouldn’t be taught to complete novices, so you have to find a good trainer and knock out the prerequisites. It’s also not “sexy” like carbine training, it’s not an excuse to buy cool guy gear, and it’s not a skill you can demonstrate at the next 3 gun match. But I think it matters.
That being said, don’t knock long gun courses either, I think they are also important.