Essentially if reminders were queryable via JQL then that would reduce the privacy of some reminders. Maybe I could make this a per-site setting? If you could please comment on that issue with your use case and if it is still a problem for you then that would be much appreciated.
Ah! That is a different and better feature request! You don't actually need a JQL query for me to show the reminders on the Dashboard, all I need to do in my app is create a dashboard item: https://developer.atlassian.com/cloud/jira/platform/modules/dashboard-item/
That is much more doable and does not impact the privacy of the reminders! I have created https://ecosystem.atlassian.net/browse/MR-99 to track this.