@Iggi:
You have several options which all require a lot of work.
This way you can get for example an old firefox (50) and an old version of Libreoffice installed and working.
Unfortunately not all software in the repos and on snapshot are available or give a bus errors and won't work.
For example all kde related stuff is not installable due to conflicts and missing packages.
If you go further and use for example the packaging system pkgsrc from NetBSD, you can get alot of stuff to compile, like almost the complete kde software and also a lot of stuff can be compiled that is then running without a bus error.
But this is even more advanced, it will take a lot of time and there a lot of compile problems to track on the internet and work around as this is optimized for NetBSD.
I trained a whole year on NetBSD Sparc64 to get everything up and running and then transplanted this knowledge to use pkgsrc on debian sparc64.
It also is by now way working out of the box and needs lots of manual intervention, but lets you compile a lot of software with the exception of firefox52, thunderbird52, and an older seamonkey. These seem to be too optimised to run on NetBSD Sparc64. I'm stuck on bus errors for those while they do run on NetBSD sparc64.
The reason why i want to use debian sparc64 instead of NetBSD is that on NetBSD there is a recent java, libreoffice, xrdp and more not available.
Debian sparc64 is an unofficial port and if i am not wrong, i think Adrian is almost the only person maintaining it.
Also sparc is heavy on the decline and no mainstream OS used for desktop work anymore. So a lot of the bugs are not reported and visible upstream.
And debian is one of the last linux distributions even to have a port. Once the kernel drops it (just happened to ia64), or Adrian stops supporting, i gues it will all be gone and i am forced back to NetBSD.
For now I found my peace in combining debian and pkgsrc. This will lead to a somehow complete desktop software collection.
Regards,
Connor