The Huawei P20 Pro has received a mediocre repair score during its teardown over at ifixit. The score given was four, which is out of ten with ten being the easiest to repair, and it's likely a combination of the use of glass material for the phone's backing, the waterproofing, and other factors which have made this device a little more than a challenge to fix if parts need to be swapped out. In fact some of the issues that can be found with repairing the Huawei P20 Pro are just about the same issues that were discovered with repairing the Samsung Galaxy S9, another phone that was recently torn down and received the same exact score in terms of repair reliability.
According to ifixit, the Huawei P20 Pro does have some a lot modular components which makes those in particular easy to replace, but just like with the Galaxy S9 the use of glass for the back in addition to the display panel on the front increases the risk of breaking something, which would then make for more work and more repairs, and more parts to have to order in the event that some breakage comes along.
Battery replacement is another area where the P20 Pro seems to give a challenge. Swapping out the battery for a new one is doable but it'll require more than just the part and a little know-how to get things going, as it's stated that time and effort are factors here, meaning you will likely want to have quite a bit of patience to get through the battery replacement and be willing to put in some effort and work through the difficulties. The Huawei P20 Pro doesn't have the lowest repair score of any device, but it's far from the easiest to repair as well, so if you're looking for a phone that won't present any hiccups during the fixing process you may want to reconsider on Huawei's latest.