trying to identify the issue with a mugo pine

[Strongbox18]

hey everyone i recently purchased this mugo pine and did not notice the large area of deadwood on the main trunk as the bark was still intact at the time and i did not pull away the dead bark that looked to be chewed away until the day after i got the tree home and there seem to be 3 pin holes that you can see in the pictures. it appears that it happened quite some time ago and has healed but if it is some sort of bug or fungal disease i would like to get it sorted out so i do not risk having it spread to any of my other trees. there is another smaller branch that seems to have the same issue, it mainly seems like the top of the branch sort of died back, overall the tree seems healthy other then this, any input would be greatly appreciated.

 

[Wires_Guy_wires]

It looks like there have been some kind of beetle larvae chewing away your bark, killing part of the tissue below.
The sawdust is a good indicator for that; fungi wouldn't leave sawdust, but they would instead leave compost-like degraded powder.

I would treat for woodworms/larvae. Systemic insecticides aren't transported to dead wood, so the treatment there can be a little harder since you'll need to soak the wood somehow.
Here in Europe we can't get the same insecticides as you guys in the US. So I'm hoping that someone will chime in with some advice about what to use.