I'd be willing to put each issue on its own 12 month timer, but I can't find an easy way to set that up - it looks like all the existing stock GitHub actions are for other management workflows, such as only closing issues if they are stale (inactive for a period of time), whereas I want to automatically unconditionally close an issue after a time delay.
If anyone can point me to something easy that does that by mid-January I'll set that up, but otherwise I'll just manually close everything as originally planned - I'm too busy to spend long trying to figure out how to do custom GitHub actions.