As a self-hosted Trello alternative, I use OpenTasks[0], created some Lists to sort my different kind of notes, and sync this between my machines with DAVx5 and Nextcloud. Not as streamlined as a trello, but hey, FOSS and self-hosted. On desktop I can view my tasks and lists with Nextcloud's web app, or Thunderbird's Lightning addon. With OpenTasks, one task can have a title, a detailed description, a checklist, start and due dates, completeness status, even priority - I usually just use the title, and often the checklist, excellent for groceries and household chores.
You could also try Wekan[1], which is awesome on desktop, but I found the mobile interface unusable.
My philosophy is that my life is not important, I'm not unique, and I'm not influenced by ads, so I might be wrong, but tech companies are literally wasting their cpu time and database space storing info about me.
So they can store all they want while I enjoy their free products.
I use a combination of nextcloud deck + all its other addons. I've installed it on a rasberry pi and a simple zerotier setup so that my notes are accessible over the internet.
You could also try Wekan[1], which is awesome on desktop, but I found the mobile interface unusable.
[0] https://f-droid.org/en/packages/org.dmfs.tasks/
[1] https://wekan.github.io/