Not today, unfortunately. I was hoping Asset Library would do this, but it doesn't look like it. It would be really helpful, so if something needs changed, it changes it everywhere.
This idea will help for just getting one-off UIs into another flow, but it won't solve the changes issue: For getting a UI into another flow, just copy an action that has that UI in it. It will bring over the action and the UI, then you can delete the action if it's not the action you need.
This idea will help both in using a series of steps containing UIs as well as solve the changes issue: You can call one flow from another. For instance if you have "LoginToQuickBooks" as a 6-step series with multiple UI elements, just make that it's own flow. Every Flow that needs to use "LoginToQuickBooks" can call that flow and you only have the one place to change it.
Best of luck!