Adding ToolButton Merge Selected Features to plugin

Question

I've created my own plugin which also includes Standard QGIS-ToolButtons. I've been trying to add the "Merge Selected Features" (Advanced Digitize Tool Bar) Tool into my Plugin.

How do I add it to a Plugin?

I've tried to add it the same way I'd add the "Split Parts" Tool Button:
Example:

 splitParts = self.iface.actionSplitParts()
 splitParts.setToolTip(self.tr('Split selected Object'))
 self.toolbar.addAction(splitParts) 

but there's no "actionMergeSelectedFeatures" call.

I've also tried stuff such as:

self.iface.advancedDigitizeToolBar().actionMergeFeatures()

self.iface.QToolBar('mAdvancedDigitizeToolBar').QAction('ActionMergeFeature')

self.iface.mainWindow().findChild(QAction, 'mActionMergeFeature').trigger()

and also tried a similar approach as I did with the ExportToSpreadsheet Processing Tool (https://gis.stackexchange.com/a/447931/135540)

and I also tried to work with "dissolve" instead as well (ex. processing tool native:dissolve)

but I'm not getting anywhere.

If needed, most of my code is visible in the link I posted above.

Answer 1

The action object name is 'mActionMergeFeatures'. So the following works:

self.iface.mainWindow().findChild(QAction, 'mActionMergeFeatures')

E.g.

class TestWindow(QMainWindow):
    
    def __init__(self, iface):
        self.iface = iface
        super(TestWindow, self).__init__()
        self.setGeometry(500, 500, 500, 350)
        self.toolbar = QToolBar(self)
        self.addToolBar(self.toolbar)
        self.a = self.iface.mainWindow().findChild(QAction, 'mActionMergeFeatures')
        self.toolbar.addAction(self.a)
        
dlg = TestWindow(iface)
dlg.show()

Result:

Answer 2

So thanks to @BenW I was able to get the solution. It was similar to what I had tried, but I had integrated it wrongly. I know integrated it directly to the button instead of separately:

self.actionMergeLayers = QAction(QIcon(':/plugins/unterhalt/icons/mActionMergeFeature.png'), self.tr('Objekte verschmelzen'))
MergeLayers = self.iface.mainWindow().findChild(QAction, 'mActionMergeFeatures')
self.toolbar.addAction(MergeLayers)

Don't even need the self.actionMergeLayers.triggered.connect() part.

Thank you very much for your help. I guess I was just thinking too complicated..