Hackers wouldnt share their real meaty ideas.

best to think own.

find a problem you or close family member faced.

will you work on it in long term if it sticks.

are you interested in the idea.

if you find something incredibly interesting and if it checks the above three then also can go for it.

example - most of us here find stacker news, mastodon incredibly interesting. and SN, mastodon solve problems, we can work long term on it so making SN for x , mastodon for x are validated. unless you have a better idea which will be better option as with own unique idea one can be first to go to market.