README.md per project with a task per line, sorted by priority, is what worked for me. Example:

# v1 MVP

- skeleton project: with hello world.

- database: add a database to the project and connect to it using code.

- login/logout: add users table and create a simple login/logout screen.

# v2

- reset password: allows user to click on forgot password and receive a new password link in their email.

- themes: tailwind or bootstrap.

And this is what I tried but failed:

GitHub Issues: not ergonomic enough. Requires many clicks and typing to search issues once you get past like 10 issues.

Trello: too simplistic and easy to desync with code.

Joplin: really nice but also easy to desync with code.

Google Docs: nice but also easy to desync with code.