If your relative also needs something on Android, you might look at https://software-lab.de/StenoBoard/README https://software-lab.de/StenoBoard/README I wrote

If your relative also needs something on Android, you might look at https://software-lab.de/StenoBoard/README https://software-lab.de/StenoBoard/README I wrote it when I developed a Dupuytren Contracture on my hand last year, and find it very comfortable and efficient. It is my sole keyboard input now.