It’s been over a month and no one has to reply, so let me be the first! I am a professional pianist and Improvise all the time in my practice sessions. In my opinion, it helps to know certain structures or musical devices. If you know a chord progression, play the chords in the left hand on loop and practice a loose melody on top. From there, switch the roles and try to improvise the bass. Little by little, you can develop your technique as we do with all things, but to improvise well and fluently, you need to train your mind. You need to have knowledge and confidence in your music skill to execute complex passages. Start simple and get more complex over time. Attached is my little demo just doing C-F-G chords in the left hand and going for it with my right hand.
YCF | Sample Improv.mp3