Let’s start with an user case.
First take your working workspace with your channels and a lot of emails by customers for support or maintenance.
One of this customers is more important then others so is important to be fast to talk with them instead use email.
Also to improve the timing on following them and divide the questions by long discussion or simple messageslike “just press that button”.
Both of them has their Slack workspace with a lot of users but no one want to pay a lot of money to Slack to bridge natively a channel (yes it is isupported since a while but require to have a premium plan).
MatterBridge is the solution because is not heavy as resource (on my settings like just 100mb of ram) and is very easy to configure using their gateway system.
Basically, also if it is not written in the docs, is possible to bridge the same service between 2 differents gateway and in this way it is possible to achieve what we need.
Also Matterbridge support the sharing of files because download and reupload in the various workspaces.
Of you are wondering the setup part check the docs that is complete with screenshot.
channel="[another channel name]"