Adding dbus authorisation to "org.freedesktop.Notifications" and "com.lomiri.hfd" would solve the confinement problem. Also
https://gitlab.com/ubports/development/core/apparmor-easyprof-ubuntu/-/blob/main/data/policygroups/ubuntu/1.2/push-notification-client
Also the filtering in this file for Postal is probably buggy as I get
[POST] >> QDBusMessage(type=MethodCall, service="com.lomiri.Postal", path="/com/lomiri/Postal/alefnode_2ewhatsweb", interface="com.lomiri.Postal", member="Post", signature="", contents=("alefnode.whatsweb_whatsweb", "{"notification":{"card":{"actions":["appid://alefnode.whatsweb/whatsweb/current-user-version"],"icon":"/opt/click.ubuntu.com/.click/users/@all/alefnode.whatsweb/icon.png","persist":true,"popup":true,"summary":"Whatsapp test"},"sound":true,"vibrate":true}}") )
[POST ERROR] "An AppArmor policy prevents this sender from sending this message to this recipient; type=\"method_call\", sender=\":1.483\" (uid=32011 pid=27477 comm=\"/opt/click.ubuntu.com/alefnode.whatsweb/current/bi\" label=\"alefnode.whatsweb_whatsweb_0.2.8 (enforce)\") interface=\"com.lomiri.Postal\" member=\"Post\" error name=\"(unset)\" requested_reply=\"0\" destination=\"com.lomiri.Postal\" (uid=32011 pid=3117 comm=\"/usr/lib/lomiri-push-service/lomiri-push-service \" label=\"unconfined\")"
But anyway even unconfined postal does not work for me.