Yes and no. Niger Triggers tend to be quite docile (though there are a few exceptions), while Coral Beauties are fairly spunky angels. So long as the two are introduced at the same time and are similar in size, there should not be any problems related to aggression. However, eventually the trigger will grow large enough that the angelfish will be viewed as food. It's best not to mix these two, problems are almost inevitable.
Little shrimps would be out of the question, but most larger cleaners, coral bandeds, etc. would be out of reach for a 2" niger. Clams may be at risk down the road - but never a problem for me (I've had three different ******).
When it gets bigger the larger motile inverts would be at risk, but if they were together from day one, the chance is much, much reduced.
I kept a Coral Beauty & Niger together for 3+ years - and I HATED the CB ("coral bully"). ****** are planktivore and crustacean eaters - won't view the CB (or any but the tiniest of fish) as food at all - so minimal risk there.
As with most things, there's some risk for either of those fish, but for my money and experience, the Niger will be MUCH more reef safe in terms of corals and sessile inverts than the pygmy angels or even tangs... It's really the shrimp, and then crabs as the fish grows, that are problematic.