[Twirrim]

I used this approach to start iterating on some Arm builds before I got access to any of the Arm servers they were introducing at work (Oracle Cloud Infrastructure).

I'd started out using a full emulation VM, and it was alright, but the cost of emulation was crippling for parts of the build process. IIRC one part of the build process was pulling in python libraries that didn't have arm wheels, and that took a bit of work to compile even on native architecture. Add in the overhead of full system emulation and it really hurt the iteration process. Especially as I worked my way from "Finally got it to build!" through to "Got the build repeatable from scratch!"

The binfmt / container approach dramatically reduced the amount of emulation being done, resulting in phenomenally faster build times.

Then I finally got access to an actual Arm instance and the entire process took even a fraction of that time.