@MartinK, I was thinking along the same lines and wanted to try. Last week I’ve got the maps stack compiled for Fedora at OBS (https://build.opensuse.org/project/show/home:rinigus:maps) using the same RPM SPECs as for Sailfish. So, it is a matter of adding SFOS target to test.
Looking at Fedora target, META (https://build.opensuse.org/projects/Fedora:32/meta) seems to be doable for SFOS as well. Project config is a bit more complicated (https://build.opensuse.org/projects/Fedora:32/prjconf). Corresponding SFOS variant has significant amount of settings at https://build.merproject.org/project/prjconf/sailfishos:3.3.0.16
From legal POV, it seems that Suse expects it to be used by open source projects. As to whether we can compile against closed-source bits, I don’t know. I would have guessed that we can compile our OSS against SFOS bits, but see https://en.opensuse.org/openSUSE:Build_Service_application_blacklist .
There is a difference in use of sb2 (SFOS OBS) which is not used by Suse. Although, we have large fraction of Nemo stack compiled at Suse against Fedora 32 (for ARM as well). Let’s see how it works on devices.
From the last month experience of using Suse OBS, I can see that it is significantly loaded with many projects. In particular, ARM 32-bit does not have much worker nodes and you could end up waiting for a while with them. Aarch64 is OK, x86_64 has sometimes longer delays with OBS repository state recalculations. All in all, it is slower and you do notice it than SFOS OBS.