I tried the injection script (and variations to it) numerous times today and they failed every time with SecurityException: Shell does not have permission to access user 10.
I'm on the latest stable GrapheneOS (2026100201).
Looking into the git history I think basically the script was exploiting CVE-2025-22442, which was fixed in https://github.com/GrapheneOS/platform_frameworks_base/commit/38400ae033667b7a7ad02a00b6b8ebb83ac6eafb
This needs an OS-side change (Play installed into the profile at creation, as the closed PR did). It's no longer possible to install packages before the user gets locked down.