I was able to get it working with the code below:

layer1 = QgsVectorLayer("Point?crs=EPSG:4326", "my layer", "memory")
QgsProject.instance().addMapLayer(layer1, False)

root = QgsProject.instance().layerTreeRoot()
node = root.addLayer(layer1)

indicator = QgsLayerTreeViewIndicator(iface.layerTreeView())
indicator.setToolTip('Test')
indicator.setIcon(QIcon(':/images/themes/default/mActionIdentify.svg'))
indicator.clicked.connect(lambda: print('indicator clicked'))

view = iface.layerTreeView()

view.addIndicator(node, indicator)

def rows_inserted(parent, first, last):
    nodes = root.findLayers()
    for n in nodes:
        if n.layer().id() == layer1.id():
            if not view.indicators(n):
                view.addIndicator(n, indicator)

conn = view.layerTreeModel().rowsInserted.connect(rows_inserted)

After removing layer, clean up by disconnecting signal/slot and deleting indicator object:

QObject.disconnect(conn)
del indicator

Screencast shows this working:

Based loosely on source code in qgslayertreeviewindicatorprovider.cpp which would probably take care of this nicely but does not seem to be exposed in the Python API bindings.

I was able to get it working with the code below:

layer1 = QgsVectorLayer("Point?crs=EPSG:4326", "my layer", "memory")
QgsProject.instance().addMapLayer(layer1, False)

root = QgsProject.instance().layerTreeRoot()
node = root.addLayer(layer1)

indicator = QgsLayerTreeViewIndicator(iface.layerTreeView())
indicator.setToolTip('Test')
indicator.setIcon(QIcon(':/images/themes/default/mActionIdentify.svg'))
indicator.clicked.connect(lambda: print('indicator clicked'))

view = iface.layerTreeView()

view.addIndicator(node, indicator)

def rows_inserted(parent, first, last):
    nodes = root.findLayers()
    for n in nodes:
        if n.layer().id() == layer1.id():
            if not view.indicators(n):
                view.addIndicator(n, indicator)

conn = view.layerTreeModel().rowsInserted.connect(rows_inserted)

After removing layer, clean up by disconnecting signal/slot and deleting indicator object:

QObject.disconnect(conn)
del indicator

Screencast shows this working:

Based very loosely on source code in qgslayertreeviewindicatorprovider.cpp which would probably take care of this nicely but does not seem to be exposed in the Python API bindings.

I was able to get it working with the code below:

layer1 = QgsVectorLayer("Point?crs=EPSG:4326", "my layer", "memory")
QgsProject.instance().addMapLayer(layer1, False)

root = QgsProject.instance().layerTreeRoot()
node = root.addLayer(layer1)

indicator = QgsLayerTreeViewIndicator(iface.layerTreeView())
indicator.setToolTip('Test')
indicator.setIcon(QIcon(':/images/themes/default/mActionIdentify.svg'))
indicator.clicked.connect(lambda: print('indicator clicked'))

view = iface.layerTreeView()

view.addIndicator(node, indicator)

def rows_inserted(parent, first, last):
    nodes = root.findLayers()
    for n in nodes:
        if n.layer().id() == layer1.id():
            if not view.indicators(n):
                view.addIndicator(n, indicator)

conn = view.layerTreeModel().rowsInserted.connect(rows_inserted)

After removing layer, clean up by disconnecting signal/slot and deleting indicator object:

QObject.disconnect(conn)
del indicator

Screencast shows this working:

Based loosely on source code in qgslayertreeviewindicatorprovider.cpp which would probably take care of this nicely but does not seem to be exposed in the Python API bindings.

I was able to get it working with the code below:

layer1 = QgsVectorLayer("Point?crs=EPSG:4326", "my layer", "memory")
QgsProject.instance().addMapLayer(layer1, False)

root = QgsProject.instance().layerTreeRoot()
node = root.addLayer(layer1)

indicator = QgsLayerTreeViewIndicator(iface.layerTreeView())
indicator.setToolTip('Test')
indicator.setIcon(QIcon(':/images/themes/default/mActionIdentify.svg'))
indicator.clicked.connect(lambda: print('indicator clicked'))

view = iface.layerTreeView()

view.addIndicator(node, indicator)

def rows_inserted(parent, first, last):
    nodes = root.findLayers()
    for n in nodes:
        if n.layer().id() == layer1.id():
            if not view.indicators(n):
                view.addIndicator(n, indicator)

conn = view.layerTreeModel().rowsInserted.connect(rows_inserted)

After removing layer, clean up by disconnecting signal/slot and deleting indicator object:

QObject.disconnect(conn)
del indicator

Screencast shows this working:

Based loosely on source code in qgslayertreeviewindicatorprovider.cpp which would probably take care of this nicely but does not seem to be exposed in the Python API bindings.