GitLab to push branches to remote server

Not sure if this is possible with GitLab so an investigating options.
I am trying to devise a way for testers to deploy branches to staging for testing.

I have git installed on my PC and can push a branch to a remote staging repo no prob.

Issue is I may have 3 branches developed awaiting testing and I want the testers to push whatever branch they are ready to test. Getting them to install git is not going to happen so what I want to investigate the possibility of them to Log into GitLab and then:
Select a Branch and click “Push to Staging” (or something similar) which then pushes the selected branch onto the remote staging server for them to test. They can also switch between branches at will.

Is this even possible from within GitLab?