I would avoid a red-dot sight or light. Extra weight, bulk, introduces multiple possible points of failure which are compromising if you rely on them.

I'm of the opinion that if you have to change anything other than the sights or grips on a EDC handgun, it's not suitable for EDC. 

Wanting to change things usually introduces problems. Like the guide rod on a Glock, in the past it was common to change the nylon rod to metal, and it sometimes caused the recoil spring to bind up. The nylon never failed. And lighter springs on revolver triggers - sound like a good idea until the hammer drops and nothing happens.

I tend to agree with you. EDC is about 100% reliability. They are good enough - as is - from the fact.

How about aftermarket triggers? The squishy trigger of the S&W M&P 1.0 pistols is really not ideal.

As far as triggers go, you may change the reliability of the gun if you change the trigger.

Is the replacement trigger as reliable and as safe as the original ? Will the gun remain drop safe with the new trigger ?

My preference is to practice with the original and reach adequate proficiency.  If the trigger is unfamiliar enough to consider replacing it, you may just need more trigger time. 

Glock factory triggers are notorious for feeling spongy. World class sport shooters do quite well with it as is. 

Nothing other than sights and grips for me. Most of the 'upgrades' people do to EDC guns fall into the magical spending or Instagram worthy categories in my opinion.

I want everything I could conceivably carry to have the same sight picture and for them to point as naturally as possible.