By experience, getting Firecracker to run well on M-series macs is quite the undertaking. I'm not at all surprised Encore decided to take this path considering their customer base!

At Lovable we decided to spend ~1 engineering month getting our sandbox infrastructure to be 100% runnable on Mac and on Linux with predictable builds using Bazel etc.

But we actively decided to take a different route than Encore and run nested virtualization, which on macOS means vfkit -> QEMU -> Kind + Firecracker vm(s). It's been invaluable to get the same development and testing tools on both platforms tbh.