Having bought an 8 pin TXS to try, I fitted it to a Hornby 37 yesterday using the supplied speaker.
The app is extremely intuitive and takes you through each step. Firmware updates took a couple of minutes and sound download was about 15 minutes. Then it was time to test. No problems found. The sound, whilst not top notch, is acceptable. I expect a speaker upgrade will help but that is something for the future.
Overall, I was impressed at the ease of the process and the results. As a result, I am now considering fitting another couple of locos.
As feedback for those involved in testing, I am running the app on a Samsung Galaxy A52s 5G without any problems.