Envelope is a wrapper to "..." project, used as a workaround for third party bugs and features that cannot/should not be fixed within "..." project. It is also a bridge between public open source projects and their private use.
Envelope-for-"..." is actually a fork of "..." project. Envelope-for-"..." team is not related with "..." team.
Envelope-for-"..." is an extremely thin wrapper around https://"..."-url that uses the "..." license https://"..."-license-url. The "..." project, included as an unofficial submodule (./native folder), has its copyright and license holders kept as is.