This is relevant for community builders too.
Don't wait for examples from your specific sector. The difference between building a community for clowns, baristas, middle-aged fans of rock, backyard-chicken types, doctors, and accountants is not as great as you might imagine.
99% of the same community building principles apply to every community.
You still start small and grow big. You should still allow off-topic discussions. You should still have a simple, activity-orientated, platform. You should still use regular events and activities, personally engage with individual members, create content about the community etc..
Too often, principles that are deemed 'non-serious' are ignored in the belief that members will only want to discuss the most serious issues facing their sector. That's not true. Go to a local meet-up. How much time do you spend discussing the meaty, serious, stuff compared with general chat?
Many organizations are waiting for the absolute perfect example of a successful community in their sector before they know what to do. Of course, by then it's too late and their playing catch-up.
There are many things we know work well. Don't ignore them. 99% of community building principles apply to every community.