You might want to consider looking at the Components in PowerApps.
They are great for reusablity. However as menu components, you can make them work (and we do that), but there is a valuable feature that is missing from them to be fully usuable as a drop-in-menu control (without some additional controls on the screen itself).
There is an Idea on the idea forum to get that ability. If you had it, your component would just be an easy drop in menu for each screen. Feel free to look at the Idea and vote on it.
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