apkstudio VS telegram-qt

You can decompile android apps, which will give mostly the original Java Classes / functions with anonymized names (class A, function b, etc...). Framework classes and methods usually stay pretty much the same.

See for example https://github.com/robertohuertasm/apk-decompiler and https://github.com/vaibhavpandeyvpz/apkstudio (only used the first one but the seconds looks practical)

JFTR, There is also ApkStudio[0], but it is not updated since October 2020.

[0] https://github.com/vaibhavpandeyvpz/apkstudio

That's where we're now. Those free services are all (relatively) new and they still need to get some hang, but they have some enough that some kind and smart people were interested enough to develop a desktop client. Yes, in the ideal world (or at least my ideal world) people would just remembered about KDE-Telepathy and restart their work. I had some hope a couple years ago but definitely one man just can't keep up with the huge amount of work it needs, not just in KDE-Telepathy but in upstream Telepathy. Hell, it's a miracle that things like Telegram-Qt still move, albeit very slow.