If you or a friend has a PS5 with a PS Plus Premium subscription, you can trial the game for two hours. Your progress will transfer over if you decide to buy, but that’s as close as you’re going to get to a demo I think.

TickTick sounds like a good option for what you want. It’s a very simple tasks list app but allows you to share those tasks with other users.

https://ticktick.com/

Strongly recommend this too. It’s takes a minute to get used to but once you do, it feels very natural.