And I must say: I like it a lot. Sure, I do not get quite the detailed analytics data with Fathom as before with Matomo, but I got used to it pretty fast. The beautiful UI of Fathom speaks for itself. Everything you need to know about your website is available on a single page. No nested submenus, etc.
A big plus: My websites are free of those filthy cookie banners that no one likes, and that distract the visitor.
The API of Fathom is still a work in progress (at the time of writing) but you can request early access by emailing the blazing fast customer support of Fathom. I did this as well in order to develop a neat little Laravel wrapper package for the API (and tracking script) because I found myself doing the same things over and over again while implementing Fathom on my websites. So I do not want to track page views of myself for example.
Disclaimer: My laravel-fathom package is still a work in progress because the Fathom API is so as well and so it may introduce breaking changes in the future.