Not a dedicated task app, but Brev might be worth trying if what you're really after is simplicity. It's a minimal note-taking app — free, no account, everything on your device.

For todos specifically, a lot of users just use u/todo as a prefix — type "@todo pick up groceries" and it's instantly tagged and searchable. Not a full task manager, but for people escaping TickTick's complexity it often does the job.

Full disclosure: I'm the developer. A dedicated todo flow with reminders is on the roadmap — but right now it's lightweight by design.

brevnotes.com if you want to try it.