Stumbled upon raysession. A GUI for NSM:
https://github.com/Houston4444/RaySession
Has some interesting features, like git snapshots (go back to previous
snapshot) and X window memory (which didn't work). Interesting if
reliable, which I don't have the expertise for, to judge.
I tried to open a NSM session in it. And got his message:
https://i.imgur.com/NZjpKMK.png
Openening the session failed the first time and the second time, I did
loose my saved JACK connections. Not for me at the moment.
Your experience may differ.
\R