You highlighted one possible option: have a client. There are multiple things used on Tor that have a client, so that's possible.

I'm not saying these options are better, but I'm saying they are possible.

Asking users for email is the point of weakness - emails run on clearnet domains and if the email providers are kneeled on, they will provide the information to a three letter agency of your choice (e.g. proton did provide info in the past).