Mastodon accounts can reach people outside the Fediverse by using posts with public visibility. There's a guide to post visibilities here:
➡️ https://fedi.tips/who-can-see-my-posts-in-mastodon-how-do-i-send-dms-in-mastodon/
Anyone can see a public post through links to the post, or posts embedded on a website. Here's how to embed a Mastodon post on a website:
➡️ https://fedi.tips/how-to-embed-mastodon-posts-on-a-website/
Mastodon accounts can also be followed by non-members through RSS readers, just add .rss to the end of a profile's web address (for example https://mstdn.social/@feditips.rss).