OK, I’ve published a “dev” release, version 1.90.dev1 as a prelude to 1.90.0
I’ve uploaded Standalone Win/MacOS versions in both Python2.7 and Python3.6 to https://github.com/psychopy/psychopy/releases
You can also now install to any python installation using pip install psychopy and this will install nearly all the dependencies (except that pyo is still not available that way).
So to get a dev version running on python3, separate from your main standalone installation you can just install Python3 and do pip3 install psychopy
The easiest way to launch the app is
python3 -m psychopy.app.psychopyApp