Several years ago, I made a program called QSOSender3 that simulated QSO interactions for learning Morse code. It randomly creates 'transmissions' to address the issue that most Morse code learning programs were focused on letters and numbers and not the interactions you would see on the air. It generates a nearly unlimited set of transmissions, with the higher speeds generating longer QSOs.
After Google complained about how out of date the program was, I decided to rewrite it and call it QSOSim. Hopefully, I have fixed all the nagging issues the original code had. QSOSim can be found on the google play store. It is free for anyone to use.