There is a first usable version of a Mastodon client app written with CAPI available:
https://codeberg.org/louis77/cl-mastoclient
A pre-built binary for Linux x64 is available on Codeberg, too.
The app is very simple, just downloads your statuses (meaning, your own posts) from your instance and let’s you search through them after it finished. A double-click opens the post in the browser.
It should work with any Mastodon™️ compatible server.
In case any #LispWorks users with DV licenses for Win/MacOS/FreeBSD, let me know if you can deliver it.