I have the same experience as you regarding progressive migrations, having done quite a few from C and C++ semi-recently. Often progressive migrations are impossible, due to a "unit" being almost the whole program, by having too many small dependencies and little hacks here and there. So you progressively migrate 20% or 30% and it works but then you hit a roadblock and you have to refactor the whole thing, which is already fragile in the first place. Also LLMs don't help here, they choke at this kind of thing quite fast.

No solution, suggestion or wisdom here, just agreement.