Ah yes! I almost do that already. With RSS as well. So you can combine communities and RSS Feeds, not mastodon users yet though. It’s kind of fun standardizing all the different ActivityPub implementations into a single data model. Mastodon timelines or users are essentially whole communities.
To be honest, building a web-version of that pipeline as a NPM package might be helpful for others, piping in all the different types of fediverse content into a single stream.