I do some beer homebrewing and (fairly or not) my first thought was of the BeerBug digital hydrometer, which was a temperature/density meter that wirelessly synced to an online service. The problem was that the website was the only way to read the data. And then the website went down for months :-/ . I didn't buy it but the whole debacle made me suspicious of depending on online services for brewing.
I'd suggest you might have more luck with a desktop app. Could wrap your existing web app with Electron or Sciter to avoid needing to rewrite the GUI. Businesses need to know they can rely on the software they use, and that's an easier sell when they can run it on their own hardware. I'd suggest a better business model is a relatively low cost for the software but charge for an optional support subscription.
