This version is good enough to actually use!
The greatest advantage of this app over ProPresenter's own remote app is that with this app, control of ProPresenter can be limited.
At maximum, this app can only advance to the next slide or go back to the previous slide, or when in grid mode, select slides from the current presentation by tapping on them.
However, the app can be configured to only control slides and slide groups that match a specific text label. This way, a speaker can control his slides and only his slides.
Finally, ProPresenter operators can send stage messages to the app, and if they send the message ALLOW or DISALLOW, they will enable or disable control from the app.
Note, this app requires ProPresenter 7.9+.