All KDE software built from git master today. I'd like to contribute .desktop files that allow Partition Manager actions tor a device or partition to appear in the Disks & Devices Plasma applet, to improve the integration between them. But to do this, you would need to be able to give the partitionmanager binary an argument corresponding to a device or a volume, since the system executes a command with the form of `[app] [argument corresponding to the device or volume]`. The binary currently accept no arguments like this. It looks like you used to be able to do this in an older version, but I tried using it and it did not work.
Yes, it was possible but not anymore. Some kind of filtering on device has to be implemented here: https://invent.kde.org/system/kpmcore/-/blob/master/src/plugins/sfdisk/sfdiskbackend.cpp#L66 There is a reason why it was removed. When we had it, it was using Solid filter to find devices. Solid was actually just abstracting away udisks, but abstraction was not good enough and broke when udisks2 was released (which I think resulted in not being able to detect devices without partition table). So at that time partition manager switched from Solid to its own device scanner. And non-working filtering command line argument was removed a bit later, I guess that's why you tried it and it did not work.
Interesting history, thanks.
Fixed by Tomaz Canabrava with https://invent.kde.org/system/partitionmanager/-/commit/479c3f4678ba95b2dc28cb28b7be93430cbec3de in 22.04!