Seems this is solved
Why Opentasks instead of Android Tasks?
I got here from the Nextcloud client on Android, which has an option to sync calendar, etc. That option leads to installing DAVx5, which led to installing OpenTasks.
I didn’t find this in the FAQs, so let me ask, why can’t Android’s own Tasks app be used instead of installing a third-party app? In doing so, I didn’t get my existing Android tasks sync’d over to my Nextcloud server.
Thanks for your help.
why can’t Android’s own Tasks app be used instead of installing a third-party app?
Because Android doesn’t have a tasks app, nor a tasks storage.
Do you mean Google Tasks? It’s not related to Android and not open-source, but a closed Google app and there is no (documented) API, so other apps like DAVx⁵ can’t access it.
Does that help?
Yes, that explains it for me. Thank you for your help.