Hi,
I have this principle in life that so far seems to work.
People stilling ideas will always be, however, your advantage is that you can have more ideas, they can't, so I would not be afraid of sharing work for people to look at what you are doing, this could lead to meeting new people, or even a publisher, and progress through life in some very unexpected ways. None of this will ever happen if you fear showing your work.
I would make a wip thread on this forum, as well as on Unity forum. I can tell you from my experience that this will attract a lot of people ( I even got jobs out of this), bu simply logging your work in the wip sections, and keep people informed about your progress, as well not being shy to help people wanting to do similar things. It will rewards you more than you can imagine ( I also speak from experience here).
I would not give out test copies though, and instead create a beta list and only share your work on that list while it's not officially public on a proper store or steam or else. you don't need a lot of testers, what you need is good testers that will indeed give feedback...
Maybe go to a Unity group meeting, if you leave in a big town, there will likely be a group nearby.
you can also make a free version with just one level, just to gain feedback, that would be ok, and you could gather some valuable feedback.
Bye,
Jean