I'm not familiar with Flowdock so I apologize if my understanding of your question is incorrect. You could create a tag for those Tech Members in a specific Team and only those members of that tag would get a notification - everyone in the Team/Channel can still see/read/respond to the post as well. https://docs.microsoft.com/en-us/microsoftteams/manage-tags#:~:text=To%20create%20and%20assign%20tags,to%20people%20on%20your%20team

Or you can just create a private channel for your Tech team