I had some luck with Focused Work, which is on Mac/iPad/iPhone, but I was using it more for the pomodoro features than the blocking.
What I liked about it was that I could add Shortcuts to do things like activate a Focus Mode when I was in a pomodoro, or play some focus music.
I’ve struggled with freelancing in the past because there’s too much freedom and not enough structure. Now that I’m medicated and in therapy maybe I should give it another try.