Migration from 2.5 to 3.x, why so difficult?

Well, you would only have xxx.things files if you originally created them. If you don’t know what that’s about then you probably originally used PaperUI instead. There’s a different UI for this task in OH3 of course.

This one?

it’s a version 1 binding, and simply not available in OH3, so no config for that will ever work here.

Or this one?