package.el and native-compilation: deterministic .eln generation across platforms?

Goal

Establish whether installing packages via package.el on Emacs 29+ yields identical native‑compiled .eln artifacts on different operating systems and CPU architectures, enabling a repeatable development environment.

Constraints and uncertainty

The native‑compilation backend automatically produces .eln files when a suitable compiler is present, but the exact conditions that trigger compilation and the determinism of the resulting binaries are not fully documented. Platform‑specific code paths and fallback to byte‑code for unsupported packages add further variability.

Open questions

• Does package.el guarantee bit‑for‑bit identical .eln files for the same package version on Linux and macOS?
• Which compiler flags or environment variables influence the native compilation outcome?
• Can a configuration flag disable automatic native compilation to enforce byte‑code only?