Brainstorms produce lists. Lists are not ideas — they are permission to feel productive for an hour. Every idea I have had that turned into something useful came from noticing the same workaround twice, in two teams that had never spoken to each other.
That is the whole method. Keep a file of things people do that they should not have to do: the spreadsheet that shadows the real system, the Slack message that is actually an API call, the person everyone asks because the documentation is wrong. When the same workaround shows up in a second place, it has stopped being a quirk and started being a product.
The advantage of working this way is that you never have to validate demand. You watched people pay for it in effort before you built anything.