Takes forever for my galaxy j7 sky pro to charge cord seems to fit loosely

In most cases the charging port would need to be replaced.

This involves firstly lifting up the adhered screen to gain access to the phillips head screws under the screen that are screwed into the mid frame to the back housing.

If you are intending to open up the phone look at this video:

https://www.youtube.com/watch?v=8fIMSW_j...

Note that it also requires a hot air rework station to remove the old charger port and a soldering iron to solder the new charger port on.

So in my opinion it is high difficulty as the risk is mostly from damaging the LCD display and the cost would be fairly high if you do not have the tools required to remove a charging port and solder a new one on.