Katharina 🍪 is a user on octodon.social. You can follow them or interact with them if you have an account anywhere in the fediverse.
If you don't, you can sign up here.
Some things I learned about the Mastodon web UI:
The profile page of a user on another server won't show all of their follows/posts. Open it in a new tab (by middle-clicking their username in a toot) to view them all.
To boost or fav a toot on an external site, copy its URL into the search box on your local instance. The toot will be shown as a search result.
@blinry It would be really awesome if it could display followers on my current instance and in paranthesis maybe the global count. If that's technically possible...
