I’m not Manton but maybe I can be helpful. I’m pretty sure you can already do that.
Instructions:
You can automatically cross-post your microblog posts to Medium, Mastodon, LinkedIn, Tumblr, Flickr, Bluesky, Nostr, and Pixelfed.
On the web, go to Account → Edit Sources and Cross-posting.
In the Cross-posting column, click “Add Mastodon” or one of the other services. You’ll be prompted to authorize your account with that service.
New posts will be cross-posted automatically to the services you choose.
Certain rules govern how your cross-posted content will appear. For example, on Mastodon…
Instructions are focused on Twitter, but the same procedure applies to Mastodon, with the chief exception being that the Mastodon character limit is 500 rather than 280.
Additional background:
To participate in conversations on Mastodon or receive replies from Mastodon users, you can enable ActivityPub in Micro.blog. This lets a Mastodon user follow your blog directly using one of these username formats:
@username@micro.blog
@you@yourdomain.com (if you have a custom domain name for your blog)
It also lets you follow Mastodon users and reply to their posts.
This is enabled by default for new users starting October 2022. For older accounts, click Account from Micro.blog on the web …