If you're looking for something besides Knightly Chess, Noctie.ai is another good option. Noctie.ai is a personal AI chess coach that plays like a human, adapting its style to your skill level and playing speed. It offers immediate feedback on your moves, flags mistakes and congratulates you when you succeed. It also offers custom tactics, training exercises and flashcards with spaced repetition to help you learn new skills. You can even play against the computer in specific openings or endgames, so it's a good tool to improve your chess skills.
Another alternative is Chessvision, a suite of apps that analyzes interactive chess content in real time from around the web. With a browser extension, ebook reader, phone app and video app, Chessvision offers detailed analysis and links to related videos. The phone app can scan and recognize chess diagrams in printouts and digital documents and show them on an analysis board and match them with YouTube videos. The service also offers subscription plans to access different features, so it's a good option for chess fans.