I have used in the past card sorting applications to get an approximation and external validation that my priorities are somehow aligned to the ones from my stakeholders, clients or users.
It would be like giving them the opportunity to be PM for 1 hour and then I can review how they were sorted out (based on importance/impact) and classifying features to releases.
While users not necessarily would have all the angles and personas in mind, the information would be valuable for analysis and giving the right context. I feel "ideas" is sometimes not enough as the only thing that I can use is the number of votes... but not as a comparison to other competing needs and requirements. It is not about generating new ideas but getting the right priorities for the existing ones.
Thank you for the note. We've received some requests over time for more surveying capabilities with ideas to better understand feedback and help PMs more effectively prioritize ideas and features.
There's a similar idea which we've noted as "likely to implement" which you can see here: https://big.ideas.aha.io/ideas/APP-I-991
It seems that the above idea may help to achieve the same goal that you are looking for.
At this time, we're unlikely to provide features board type functionality within ideas, though the obvious workarounds would be to give them direct access. However, we hope that the other referenced idea may be of interest. By voting on that idea, you'll continue to get updates as it progresses.