iFixit — the popular tech teardown blog — dissected the latest iPhone 12 mini. Here is the link to the full teardown: https://www.ifixit.com/Teardown/iPhone+12+mini+Teardown/138505. It assigned a score of 6/10 for repairability.
It seems like, it is easier for a newbie tecKids to change the screen and the battery, the most common repairs. It is amazing that Apple was able to pack such a powerful machine into 5.18 x 2.53 x 0.29 inches.