and I can't figure out how to get the dx command, because on my Debian Bookworm system there is no such command! Can this problem be solved so that I can access on my system only Android SDK and development tools already available in Debian?
dx is deprecated, you should use d8, see https://android-developers.googleblog.com/2020/02/the-path-to-dx-deprecation.htmlBut dx is still packaged for Debian, it's part of the dalvik-exchange package, and works if you compile the Java code with the appropriate flags or with an older JDK)
I've documented how to create an android package with C++, Kotlin, and Java code without using Gradle:
https://fekir.info/post/how-to-assemble-an-android-program/