The main piece of feedback that we got when pitching this idea was that you're going to end up as a master-of-none. Yes, we could give you the tools to set up Customer, Ticket, etc. objects. But in order to win over Zendesk, you're going to need all of the features they provide. Chat, ticket queues, automation, etc. Business users also don't want to be architects - a turnkey solution that solves 80% of their use case is better than a blank slate that they have to start thinking about schemas, relationships, etc. The old saying "nobody ever got fired choosing IBM" can now just as easily be applied to VP of Sales picking Salesforce.
That being said, there ARE tools to do this: Quickbase (enterprise) and Airtable come to mind. I'm curious if the author has looked into using one as their base instead of Google Forms/Sheets.