It seems gprbuild is not available (at least for TW). It would be nice to have it in all OpenSuse distros. It is available in Ubuntu. If you need help on installing and testing, I’m there.
Other important packages related to gprbuild are gtkada and xmlada.
The install instructions provided by AdaCore (the maintainer) are incomplete. So I wrote some install scripts as a workaroud. It could be a start for implementing gprbuild, gtkada and xmlada.
As this is the user forum, this seems like the wrong place.
If you want to see this packages in openSUSE, set up an OBS project, convince somebody to properly maintain it (ask at ML) or do it yourself. If the package fullfills some quality standards and has the right licence, ask for incorperation into factory.
There are OBS home projects for them. You may consider contacting users who setup these projects.