_(w)environ[] do have a distinct allocation chunk for each entry, so that _(w)environ[i] pointer and (pointed) string don't change when updating/deleting any other entry.
Proposed implementation still differs from native: - allocation is done on process heap, while native uses msvcrt's heap - first ANSI allocated _environ[] doesn't have per entry allocation. This is only activated after a change (update/deletion) to _environ[] is made.