I found a way to evolve Feebas without walking the 20 km. Not sure if it’s old news or not. But if you switch buddies really fast and go to the buddy screen, you can just evolve it before the evolve button gets grayed out. I have uploaded a picture of Feebas walking 14.6 km but evolved. So yeah, not sure if this is new and I apologize if this is old news.
Here is a video: https://youtube.com/shorts/qKojsav7ASM?si=QB6eH9hSALmKcsTq
by NapkinZhangy