What to do with spare research topics?

I believe the most 'formal' way to share these would be to write a survey of the area that your open problems relate to, highlighting each problem. This adds a publication, and anyone who solves one of the problems is likely to cite it. Moreover, if the survey is sufficiently in-depth, it can generate a large number of citations as an introduction to the area.

An incentive you should recognize is time: worrying about these problems takes time away from what you do want to prioritize.

I recommend the following experiment, and will assume for sake of discussion that the ideas lie within mathematics. Take one or two of the ideas that you consider expendable, and spend 30 minutes writing a MathOverflow post about them. Post that on MathOverflow, and then sit back and wait. If you do it with proper attribution, people may solve them and give you credit for your contribution, or otherwise make progress that you might deem satisfactory. Or they might be ignored for a while. The basic idea has been put out there, and you can decide to reprioritize it and then later post what progress you have made as a partial answer.

The point of the experiment is to see how you feel about letting something go. If it works well for you, you can repeat it with other things. If it doesn't, you can stop at the second or third expendable idea this way. I have the hope that sharing some of your low priority expendable ideas will bring more satisfaction than waiting for the right time to reveal it to someone. As my background is mathematics, I suggested the MathOverflow forum. You will have to find or create an appropriate forum to share these ideas.

The long term solution is: 1) obtain funding, 2) build a research group, and 3) delegate. Goto 1. (Somewhere along the line, get tenure to ensure that this loop will continue indefinitely.)

These task will require coherence across your research ideas.

Firstly to have a convincing enough thrust for funding agencies to invest in you.

You to have a narrow enough focus for your research group to work cooperatively (or at least, to be able to read and comment on each other's work).

Finally, you'll need ideas to come in big enough chunks for PhD students to write dissertations on.