How do you make a flow available to a single team channel in Microsoft Teams?
share the flow only with the users in the channel, then advise them to add the URL to their list of saved links in Teams. source 'navigate to the Strategy and Planning team in Teams and add the Flow tab to the General channel.'
you cannot restrict users at the channel level
create a new channel called 'Shared Teams Flows' and post a link in the team chat
in the channel, click 'Add a tab' and select 'Flow', then share flow with matching user group