Many operational spreadsheets are already relational. They have customers, orders, projects, budgets, assignments, stages, and status changes. They join ideas together, even when the tool only exposes cells.
The difficulty is not the idea of relationships. The difficulty is the ceremony around expressing them.
EndFun is being shaped around the parts that spreadsheet users already understand: rows, groups, filters, summaries, and live calculations. A relational model should not require jumping straight to a database schema, backend service, and custom admin interface.
That means EndFun can borrow from programming languages and databases without making the workspace feel like either one. The useful surface is still direct: define the data, define the logic, and inspect the result.
The SaaS product will grow around that workflow. The current browser demo is an early window into the language and workspace direction.