Granted, this is now almost a decade now but I was trained with the HK P8 which, according to what I can find, has a trigger weight of 24N (SA) and 55N (DA)

This would be 2.4kg force or 5.6kg force needed for pulling the trigger.

But as you said, it would make sense that even this is easily overcome depending on how you pull the trigger and the thumbs would be stronger doing that, especially with both hands.

I have seen that while doing a bit of research that the strength needed can be lower for shooting competition which also makes sense but there you have a trained person in a controlled environment for a very specific purpose.

I have a serious question here that I always get when I read news like this. As someone not from the US but having experience with guns through my military training, how is it that toddlers can even pull the trigger of a weapon?

When we had the training for the pistol it was difficult to pull the trigger. IIRC it was even stated that this was by design so that you can’t pull the trigger by accident.

Are there no regulations for such a thing in the US or are toddlers that strong to do it anyway?