After you get it installed, you can make a shortcut by right clicking on the desktop and select "Create Launcher here"
I just called mine NanoVNA Saver and browsed for an unused system icon. The command for my system was
python3.7 /home/andrew/nanovna-saver/nanovna-saver.py
Procedure may be slightly different with Mate. Also of course your path will be different as well.
As a side note, you can also install AntScope 2, the RigExpert software. It won't connect to the NanoVNA but you can open the saved files to play around with.
You'll want the Ubuntu 18.04 version for Mint 19.3
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Andrew Harmon - KD5RKO
Andrew Harmon