One Question though: on Debian 12 (ppc) was able to install the required Java version for VISICUT (I think it was 17 or 18), so I could build Vorsicht from source.
Visicut is an open source lasercutter app.
Is it possible to build a more modern version on MP too? I saw in the source repo versions up to 22.
You mean a newer OpenJDK on a MacOS on PowerPC?
It obviously won’t work if you just try to install it from MacPorts, since JDK needs itself to build, and there are none for ppc. It should be possible (in principle at least) to build JDK versions sequentially (AFAIK, it won’t allow to “jump”), so it will take fixing and building about 10 versions. That will be a huge work.
Keep in mind also, that at least at the moment it builds without GUI. No idea if apps of your interest need that or not.
GUI should be fixable, though not Cocoa, but X11. I sorta have that in plans, but again, it is not something done in one evening.
P. S. If you wonder why something builds easily on Linux but not on MacOS: there are a few software where upstream developers made all possible bad decisions to make it extremely hard to fix anything specifically for MacOS. JDK and Qt are prominent examples. One would think that switching from one GUI to another is a matter of an appropriate configure flag, like it should be in any sanely written software; not in this case. MacOS codepath is hardcoded to use Apple native backend (which obviously gets broken with every next update), so you need to fix every instance, and do that correctly (we also cannot just cheat the build system to believe we are building on Linux, that won’t work, a lot of Linux-specific stuff cannot be supported on MacOS). It could be a matter of configure flag, if upstream did not destroy the code which could support that. But they did.