I don’t have a preference on mock up tools. I have only used a few, and I am not impressed with any of them. A pad of paper or bar napkins work fine. This would be a stand alone application (web/react) that would later have a plugin developed for that note software you mentioned previously. 
Am I getting credited at least? Haha
I’ll get back at you asap. DM me or we can chat about this on Discord.
Of course I would give you credit! Haha. And I doubt it would be monetized. If it were, we can come to some agreement there as well. I mean the source code is going to be on Github, so there is no great mystery going on here.