I would re-phrase that, I think I’d like to use an existing technology for tasks/todo: CalDAV 
- A native Todo app. As I was looking up what to use for KDE and found a Todoist client just like @direc85 suggested in this thread: Native Todoist app? However, since then I found that
mailbox.organd KOrganizer can save Tasks into CalDav (presumably) and should also be visible in Thunderbird. This is why I am now thinking to add a Todo feature based oncaldavto SailfishOS. More like tasks.org.- Bonus points: re-use the existing calendar account
- integrate with browser as “read later”
:-P