Not Another Hero

Find the local granite gnome leadership. With any luck, the head honcho will have some ambitions or ideas for expanding their power or influence. It's dangerous to risk a secession by fostering such ambitions, but granite gnome expansion is exactly what you need.

I think finding a way to extend the industry to encompass metal goods or steel smelting is the best way forward.
Increasing the market supply of metal tools will hopefully allow farming to become more affordable as an upstart, not to mention y'know. The export of said metal goods to trading partners.
Steel smelting is also a complex, profitable, labor-intensive task. It'll feed into the hypothetical metal goods industry, and it'll create jobs for the many starving laborers. Heck, even plain steel is relatively valuable.

Just keep that in mind while you explore the city.