Not sure this addresses your problem, but I do not see the need for a package (.deb or otherwise) as NanoVNA-Saver comes as a binary for Linux, Mac and Windows, no need to install anything. This worked for me on Linux Mint 20.3 (Ubuntu 20.04.5 LTS): download the zipped file NanoVNASaver.linux.zip from , extract nanovna-saver, chmod +x to make it executable and double-click (or ./nanovna-saver) to run. Optionally you can create a Menu item.
