The Best and the Worst Thing About UA to J4 Migration?

The most shocking thing for me out of everything you just said is that this is a one man operation. Mostly I would have never guessed that based on the project. Of course, Google could have done the migration and the switch part like much, much better. But it's an opportunity for you to start fresh and reevaluate what you actually need. Some people might see this as an opportunity to actually leave Google stack because of maybe some US EU data transfers or something else. Although right now it's quite not as good as we would have expected.