I don't own or use this product, but I found this on-line manual:
https://rigpi.net/downloads/RigPi3.pdfI see a great deal of talk about
closed source licensing in the manual.
I also googled up some sort of RigPi project for Sourceforge, which seems to be a source of confusion. It has a GPL open source license, but it also seems to have
no content.
It is possible, these days, to distribute open sourced and closed source units that collectively make up a product. It is a long, legally heavy discussion. I have been briefed on it by competent lawyers who study this branch of law. It is not the sort of thing that can be dealt with by the law firm of Google and Bing.
From what I can tell, there's enough easily found talk about "closed source" to make me extremely wary about redistributing this product until and unless someone can find something a lot more definitive than what Google and Bing told me, which is just enough to put me on my guard. A combination open and closed source product is (for lay folk anyway) "closed" in practice.
There are also
different open source licenses that give we, the end users, different rights as far as modification and redistribution go.
Just hearing the words "open source" is, unfortunately, no magic wand and may not be accurate in the bargain.
Sorry, more study is needed and non-owners almost certainly can't settle the question for you.