There are different features in Asana that pertain here, and they have pros and cons, and a detailed analysis is beyond the scope of this reply but I wanted to mention that.
In addition to @Richard_Sather’s great reply..
- Your request asks both to allow people to enter content but then not necessarily edit it; if you’re referring to the same person, can you explain?
- Asana Forms are a great way for someone to enter content to a project in a prescribed way and with no training; they could contribute to the solution.
- If you are on Enterprise, there are view-only licenses you could consider for those who are only viewing project info.
- @ka_nishiyama mentioned read-only links, but that shows primarily sections and task titles and I think won’t help you, but see Working with External Clients for completeness sake.
I don’t think this would pose a problem. By default guests only see what you share with them but if you put them on team(s) to which all the required projects have been shared, you can easily manage this, I believe.
Thanks,
Larry