A bit late in posting but ... Qt Creator 17.0.0 is released for Haiku, both 64bit and 32bit are released, for 32bit there seems to be an issue (which never got reported yet?) that seem to trigger a OOM on libLLVM.so.18.1 (20.1 does the same when I checked that first).
Anyway, also found out that one could use the Designer plugin, so ... Enjoy! :)