poVoq prefixes are supported, so you could use one database for many forums.
HarMan that should be possible, the thing that matters to flarum is the url
value in the config, which will be distinct. You can make that dynamic by assigning it the $_REQUEST['HTTP_HOST']
, see other discussions related to this on how to create a fallback for cli/terminal operations. Aside from that.. you might run into issues with links targeted posts in the same database but from different domains. You should really give it a go, as I haven't heard anyone else running into any issues with similar plans.
Also remember that emails sent out might use the default/fallback url value, not the value the user was visiting. There might be ways around that, or it could already work if you do not use a queue.