Starting with a clue from Brian Warner I came up with a list of interactive geometry programs.
Several of them aspire to what I was seeking — something better than pencil and paper.
The links with program name are to Wikipedia that generally tries more to way what the program does instead of selling it to you.
The following dot links are to the main site.
<p><a href=https://en.wikipedia.org/wiki/GeoGebra>GeoGebra</a>
<a href=https://www.geogebra.org/>⦁</a> iOS; <a href=https://itunes.apple.com/app/geogebra-geometry/id1294020062?utm_source=Download+page&utm_medium=Website&utm_campaign=GeoGebra+Geometry+for+Mac>Mac OS</a>, 

<br><a href=https://en.wikipedia.org/wiki/C.a.R.>C.a.R.</a>
<a href=http://car.rene-grothmann.de/doc_en/index.html>⦁</a> open source; Java
<br><a href=https://en.wikipedia.org/wiki/CaRMetal>CaRMetal</a>
<a href=http://db-maths.nuxit.net/CaRMetal/index_en.html>⦁</a> open source; Java
<br><a href=https://en.wikipedia.org/wiki/Graphmatica>Graphmatica</a>
<a href=http://www.graphmatica.com/>⦁</a> Free Trial Download
<br><a href=https://en.wikipedia.org/wiki/Kig_(software)>Kig</a>
<a href=https://edu.kde.org/kig/>⦁</a> Python
<br><a href=https://en.wikipedia.org/wiki/DrGeo>DrGeo</a>
<a href=http://www.drgeo.eu/>⦁</a>
<br><a href=https://en.wikipedia.org/wiki/Euclidea>Euclidea</a>
<a href=https://play.google.com/store/apps/details?id=com.hil_hk.euclidea&hl=en&rdid=com.hil_hk.euclidea>⦁</a> Android


<p><a href=https://sciencevsmagic.net/geo>Try this</a>!
Compass and straightedge only.
Has a set of problems to solve.
<a href=GeoSem.html>HowTo</a>
<br><a href=https://www.mathopenref.com/constinpentagon.html>cheat</a> ➔ <a href=https://sciencevsmagic.net/geo/#0L1.1A0.0A1.4L3.6A0.1L2.2A0.0A2.15L14.20L6.6L25.20A24.20A25.30L31.31L44.44L19.19L43.43L30>pentagon</a>
<br><a href=https://en.wikipedia.org/wiki/Heptadecagon>17 sided regular polygon</a>??
<br><a href=xx.a68>Looks right</a>