Basic thread spawning works on Android, but some things are still missing:

• setting/getting the thread name. This needs prctl commands PR_SET_NAME and PR_GET_NAME.
• the std synchronization primitives, which are built on futexes. Since Android uses the Linux kernel, futex support can be shared with Linux; this just requires a bit of refactoring to avoid copy-pasting all this.

(Also, we're looking for a target maintainer for Android, so please let us know if you're up to that -- basically someone we'd ping when there are Android questions, and in case std starts using a new Android API we'd hope they would be able to provide a Miri implementation.)