@jfavre - could you keep us updated on this? IMO the ideal solution (longer-term) would be to use the debian directory from salsa and use that to build paraview-5.8.0 from sources. If it works, or if you need to make any additions then it would be possible to send these upstream to the debian maintainers and help avoid duplicate efforts.
I noticed that their builds were missing a number of cmake files, since 5.7 and 5.8 introduced an extra subdirectory that the debian build wasn’t installing. After making those changes, it rebuild and installed seemingly perfectly, but then I had some strange issues that using these paraview-config files didn’t find MPI properly. I tried backtracking and attempting a build without MPI (as per the merge request), but left this is an unfinished state (ran out of time).
If you could report back here, that would be absolutely great!