A few more recommendations.
Fats Waller records were early recordings and for some that eliminates them but that's too bad as he was a genius player, writer, singer and entertainer. These solo recordings show amazing skill and are just so fun to listen to as well.

This Italian pianist does fascinating work that leans towards the avant garde. Here he takes the very saxophonic compositions of Albert Ayler in bold directions and has helped me to understand Ayler's work better. A great album.
Les Trinitaires is a live recording of a solo piano performance by Andrew Hill. I find new things to marvel at each time I listen to this. Not the easiest listen, but a very satisfying one if you make the effort.

Charles Mingus is one of my favorite musicians of all time. He was not an accomplished pianist but he could play and this is a mesmerizing album for me, delineating how he arranged and how he thought musically, and it has very satisfying performances. I've played this hundreds of times over the years.