Normal rekeying is pretty easy, if you’re careful - push out the core (the “follower” will hold your spring pins in place), dump out the old key pins, swap to the new key, and put in the new key pins, replace the core. Even when I’ve completely screwed it up (pushed the follower too far so the springs came out, mixed all the key pins together so I had to work out which was which, and more) it’s not been more than a 10-minute job.
I owe much of my career to trying to set up Linux From Scratch two decades ago. While it’s a much better experience installing Linux nowadays, there’s a lot to be said for the experience spending your weekend debugging a system will give you.