Decoding was done with the trusty old #MMSSTV which runs perfectly fine on a modern day Linux system using WINE.
The Robot36 app for Android has delivered slightly better results in difficult conditions for me, but I couldn't quickly find a decent 3,5mm audio splitter as I like to listen to what's being decoded in parallel. 😅 TRRS adapters are a mess as well, I've spent way too much time trying different resistors to get both the level and sensing on different devices right.