I have recompiled Flatpak using SFOS 3.3.0.x provided libseccomp and json-glib. This build is available through usual Flatpak distribution channel at OBS.

For devices on SFOS 3.2.1.20 (Sony Xperia Tama and maybe some others), until the update is ready, use https://build.merproject.org/project...atpak:3.2.1.20 . The latter project will disappear once we all update to SFOS 3.3.0.16 as it is not needed in future.

I expect that on SFOS 3.3.0.x, install should be clean and there are no conflicts with Jolla's json-glib. I hope it will automatically uninstall json-glib from my repo when you update Flatpak, but haven't tested it.