Thanks :)

It’s as simple as ticking off items (and adding new ones). The categories in Tasks (#tags in Cfait) and child/parent relationships are compatible (it’s all the same iCalendar standard). Tasks doesn’t understand the Blocked-by relationship but the tasks still appear.

You just need a CalDAV server to get going. I use Radicale because it’s lightweight and single-purpose so unlikely to break (and a self-hosted Wireguard VPN because I don’t have a static IP at home). For Android you also need an app to synchronize with the CalDAV server (Tasks doesn’t do it alone), I use DAVx5 (It’s all on F-Droid).