This script gets the feed of a single Mastodon user and emits the content as an Atom feed, suitable for feed readers. You could wrap this and run it on a private server, or run it in a cron job to generate a feed file locally.
The feed includes the same entries you'd find on a Mastodon website (toots and boosts). Mastodon provides an RSS feed of toots (primary/original content), but if you also want the boosts, you have to work a bit harder. The best solution would be for the Mastodon software to provide such a feed, but in the meantime, here we are.