I was assuming Heroku was tailored towards long-running/autoscaling jobs, and didn't realize it let you set up one-off dynos on a scheduler - https://devcenter.heroku.com/articles/scheduler - which would be a perfect fit, I guess I'll take a look at their Eco option!

I was also not aware GitHub let you run actions on a schedule, that could also work - but I guess you have to use artifacts for the persistence?