can anyone create channels in theory? like would it be easy for a Nouns FC client to just create a channel for each prop?

It's not yet possible on Warpcast. It's still an experiment really.
Some rumors about early next year but nothing specific.

yeah you'd just change the `parent_url`, however it won't show up in Warpcast because they only show a set list of channels they choose, *not* a channel UI for every FIP-2 reply(casts replying to a `parent_url`)

but you could totally make your own 'channel' at the protocol level then build your own client for it!!

I can do this automatically in herocast if there’s an API where I can get all pending and previous props?