Currently, according to the documentation, in order to share a project with someone, I need to copy the URL from the address bar and send it to another person. That is very very simple, but it doesn't feel "right".
Unless I would read the documentation, I would look for a button for sharing, I wouldn't think that simply sending a URL would work for other people.
Another bigger issue is that by simply having to copy the URL and then share it, it's very easy to forget that the app is not visible to others by default. I've seen this happen with shiny contest submissions: people pasted the URL to their project, but didn't realize they also needed to change the privacy settings.
I think a great solution to both these issues is to have an explicit "Share" button that can just give you the URL, but would also remind you that the accessibility setting needs to be modified accordingly.
(As a secondary question: is there a more appropriate place to reports issues or feature requests like these? I usually look to do this in a github repo Issues as that feels a lot more natural for this type of this.)