Hi Michael, I agree it may not be very straightforward to set this up and simulate a ‘natural’ conversation.
One solution is indeed having a specific flow just to deal with greetings: it will greet the user and then ask for input while presenting the most common topics (flows)…

…Alternatively, just asking ‘how can I help?’ and selecting the Greeting intent might do the trick:

Depending on how things are set up, users might write ‘hello’, submit (triggering the greeting flow), and then submitting their query… So I would keep it very simple and to test beforehand and see how it would work (if you already use a conversational channel, check how your users started conversations and use those real examples to test it).
But having something as simple as in the screenshots below will already override the bot's clarification message, which is better than nothing :-)
Curious to see how others are handling these situations, always happy to brainstorm!