ok, to answer that last question first and add more;
I dropped back to python 3.5 (from3.6) and got the same error; PyQt5 v 5.9 said installed ok
so based on that link you gave me and others saying similar, I tried
(which is where I can see libQt5WebEngineCore.so.5 actually is)
now it crash dumped on me
python3.5 GetPage.py http://www.xe.com/currency/nzd-new-zealand-dollar
QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to
Failed to read /proc/self/maps
Failed to adjust OOM score of renderer with pid 13282: No such file or
Check failed: 0 == fstat_ret. : No such file or directory
I guess that's progress of sorts. Now I know Qtwebengine 5.9 runs with python 3.5 on my Debian Sid machine (4.9 kernel), so the environments aren't too far apart.
I might try python 3.6 again with that env. var set. - watch this space. Thanks for the help so far.