https://www.sourceware.org/gdb/

https://sourceware.org/git/binutils-gdb.git

Im doing currently some work for ARM Cortex-M devices using the arm-none-eabi-gcc toolchain. For this it would be useful to have an appropriate debugger, e.g. arm-none-eabi-gdb. Native gdb does not work in this case.
Even better would be the inclusion of a package like gdb-multiarch, what e.g. Ubuntu provides.