A couple of notes on this subject of integration with Trello.
First, would it be practical, conceivable to create a Kanban system within Agenda? That may be way out in left field for what Agenda aims to do, or it might actually mostly be a UI issue of creating a layout to display some set of “Projects” side-by-side and supporting drag-n-drop of subprojects or items between those lists.
Second, I would prefer to use Trello for Calendaring, or something other than Reminders. I am personally no longer using Apple Reminders ever since the recent iOS upgrade that demands that I upgrade my Mac to Catalina to keep things synced between phone and desk. It’s no longer seamless, but I’m coping.
I am staying with Mojave for as long as I can because I personally have a lot of money invested in 32-bit apps such as MS Office, Acrobat Pro, Adobe Illustrator that will ALL have to be replaced once I upgrade away from Mojave. Reminder syncing is not worth several hundred dollars to me.
I moved from PhotoShop to The GIMP years ago and never looked back. I’m moving from Illustrator to Inkscape and it looks like with Inkscape 1.0 in May 2020 there’s now a similar improvement in core functions over “the high-priced spread”.
I would love to find an open source replacement for Acrobat Pro. I have no idea where Open Office is these days, I decided several years ago that where they were then was not professional enough for my needs. Meanwhile, my need for them and my very tight budget keeps me on Mojave, which means abandoning Reminders.
So please find another calendar functions besides Reminders. Trello would be fine.
Thanks.