Hello,
I maintain packages for XFCE and LXDE and MATE on NetBSD. I just fixed the LXDE startlxde long standing issue it should be fine now.
The sound backend for XFCE hasn't been made to work with NetBSD yet. FWIW MATE's sound applet works fine on NetBSD
Please keep reporting issues here or at my email,
youri@NetBSD.org !