The !askmeanything@lemmy.ca would be good, as would !asklemmy@lemmy.world or !casualconversation@lemm.ee. Also, I am going to gently push back on the idea that you have to make a new community because Reddit has a similar one. An AMA is not philosophically different from the posts on any of several other text-based-engagement communities. If AMA posts start to crowd out the “original” content, then a new /c is warranted, but we just fragmented everything after the APIpocalypse that discoverability is still a pain requiring steps that shouldn’t be necessary if people just want to communicate.