Just a quickie here: I'm still salty about changes to Trello, so I wrote a big pile of Perl to migrate Trello boards to GitHub issues. Everything else I could find to do it wanted to install 200+ megabytes worth of npm modules and would only migrate very small bits, like the card title or whatever. My script moves the full history over, and preserves checklists, labels, attachments, etc.
That code is over on GitHub, you know the drill.
(The public IcculusBoard that this Patreon uses is staying put for now, because it's way prettier than what GitHub currently offers, but this might change later...but this was super-helpful to get a lot of my personal boards off Trello an onto a website I spend a large portion of my day interacting with. Maybe this will be helpful to you, too.)