I simply wanted to write a user bot which reads messages from a channel (to write them to another messenger). After reading tos it seems to be a reason to get a ban, but did this ever happen for simply reading? I bet this stuff only triggers on actions.
they actually provide a pretty complete bot api that's perfect for what you want to do. since it's a bot api, the "user" will appear as a bot in discord clients, and a few restrictions will apply (e.g. bots cannot interact with each other). but for simply reading a channel, it's pretty trivial to do.
I did use it in the past using the Rust library Serenity [0] (unofficial library ofc) to make a geoguesser-like bot [1] for a private server with friends. Pretty simple to use actually! Do note they have some pretty harsh ratelimits when it comes to API calls though, so pay attention to caching when fetching data (not likely to be an issue for your usecase at it'll mostly be server-sent events.