Just tested on a Raspberry PI 4 running Ubuntu 21.10 (with the default GNOME desktop), and kblocks seems to work as expected, including graphics, sound and bug reporting opening an external (snap) browser.
This is the output I’m seeing in the terminal where I launched the application:
ubuntu@rpi4:~$ kblocks
Warning: Ignoring XDG_SESSION_TYPE=wayland on Gnome. Use QT_QPA_PLATFORM=wayland to run on Wayland anyway.
Qt: Session management error: Could not open network socket
KBlocks.Graphics: Error loading KBlocks .desktop theme ""
KBlocks.Sound: Error loading KBlocks .desktop theme ""
propsReply "An AppArmor policy prevents this sender from sending this message to this recipient; type=\"method_call\", sender=\":1.160\" (uid=1000 pid=17378 comm=\"/snap/kblocks/108/usr/bin/kblocks \" label=\"snap.kblocks.kblocks (enforce)\") interface=\"org.freedesktop.DBus.Properties\" member=\"GetAll\" error name=\"(unset)\" requested_reply=\"0\" destination=\"org.freedesktop.NetworkManager\" (uid=0 pid=813 comm=\"/usr/sbin/NetworkManager --no-daemon \" label=\"unconfined\")"
nmReply "An AppArmor policy prevents this sender from sending this message to this recipient; type=\"method_call\", sender=\":1.160\" (uid=1000 pid=17378 comm=\"/snap/kblocks/108/usr/bin/kblocks \" label=\"snap.kblocks.kblocks (enforce)\") interface=\"org.freedesktop.NetworkManager\" member=\"GetDevices\" error name=\"(unset)\" requested_reply=\"0\" destination=\"org.freedesktop.NetworkManager\" (uid=0 pid=813 comm=\"/usr/sbin/NetworkManager --no-daemon \" label=\"unconfined\")"
"Object path cannot be empty"
Unsupported return type 65 QPixmap in method "grab"
Unsupported return type 65 QPixmap in method "grab"
Invalid return type in method "addAction"
Skipped method "setDefaultShortcuts" : Pointers are not supported: QAction*
Unsupported return type 65 QPixmap in method "grab"
Unsupported return type 65 QPixmap in method "grab"
Invalid return type in method "addAction"
Skipped method "setDefaultShortcuts" : Pointers are not supported: QAction*
Let me know if there are other things you’d like tested.