This is how Investment Bets came about: you pick a ticker, a direction and optionally a target date. From there, the site tracks your bet for as long as you keep it open (or until the target date), and you can always see the % gain/loss.
The entry and exit prices are fetched automatically by the server at the respective times, so you can trust that a bet you see was legit and not just a self-report. The obvious downside is that you have to open/close them ASAP if you want to track your actual trades, but so far I haven't found that to be a problem.
All the performance is tracked as percentages and all sizing is always equal, in order to focus on performance and make it easier to share without the sizing awkwardness. Friends (or randos if you keep your profile public) can follow you, they can get notified on Telegram when you open/close a position, and there's a leaderboard showing the public accounts. The leaderboard tracks the total sum of your % gains and losses to reward consistent correctness.
Since I wanted to focus on privacy options, the private accounts are never visible except through either private sharing links or by pre-existing followers. You can also remove unwanted followers or cycle your link - but at the same time, you can switch between public/private anytime you want.
You can see the landing page, leaderboard and FAQ without making an account, but for actually placing a bet you will need to sign up.
Please let me know if you have questions or feedback!