You didn't mention what I see as one of the biggest considerations: that current cryonics costs are dominated by fixed costs, because there are so few current customers. WIth a lot more customers the chance of success could also go way up.
https://www.overcomingbias.com/2010/07/cryonics-as-charity.html
https://www.overcomingbias.com/2021/12/we-dont-have-to-die.html
Political betting had a problem relative to perfection, not relative to the actual other alternatives used; it did better than them according to accuracy studies.
Yes there are overheads to using prediction markets, but those are mainly for having any system at all. Once you have a system, the overhead to adding a new question is much lower. Since you don't have EA prediction markets now, you face those initial costs.
For forecasting in most organizations, hiring top 30 super forecasters would go badly, as they don't know enough about that organization to be useful. Far better to have just a handful of participants from that organization.
Without some concrete estimate of how highly prediction markets are currently rated, its hard to say if they are over or under rated. They are almost never used, however, so it is hard to believe they are overused.
The office prediction markets you outline might well be useful. They aren't obviously bad.
I see huge potential for creating larger markets to estimate altruism effectiveness. We don't have any such at the moment, or even much effort to make them, so I find it hard to see that there's too much effort there.
For example, it would be great to create markets estimating advertised outcomes from proposed World Bank projects. That might well pressure the Bank into adopting projects more likely to achieve those outcomes.
I comment on this paper here: https://www.overcomingbias.com/2022/07/cooks-critique-of-our-earliness-argument.html