Is this TalkBack path through Xamarin.Android UI expected? - xamarin.forms

Question

Say I create the following shared XAML:
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Button Grid.Row="0" Text="One" />
<Grid Grid.Row="1">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<Button Grid.Column="0" Text="Two First" />
<Button Grid.Column="1" Text="Two Second" />
</Grid>
<Button Grid.Row="2" Text="Three" />
</Grid>
I then run this on an Android device and run the TalkBack screen reader. As I swipe forward through the UI, TalkBack moves from button "One", to button "Three", and then to buttons "Two First" and "Two Second". This doesn't match the order in which I've defined the UI, so is this expected? I get what I consider the expected navigation of moving through the buttons in order of "One"->"Two First"->"Two Second"->"Three", when running the same UI as a Xamarin.UWP app and using the Narrator screen reader.
I've found I can avoid the unexpected TalkBack navigation if I update the UI such that certain parts of the UI are balanced in how deep the UI is defined in the XAML hierarchy. For example, if I wrap button "Three" in a Grid, then I get the expected navigation path.
I can also avoid the unexpected TalkBack navigation if I add a TabIndex to everything that I want TalkBack to reach, but that'll need maintaining as the app UI evolves over time, and as I understand things, not all types of Xamarin.Forms control support TabIndex.

Answer 1

not sure if it's a problem from designs of Grid .From shared code , I think Grid maybe set the second Row as the low level of priority .Because the second Row define the Column individually .
If that is the logic about the design of Grid . You can have a try with define the Row and Column at the same level of priority .
Code as follow :
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*" />
<RowDefinition Height="*" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Button Grid.Row="0"
Grid.ColumnSpan="2"
Text="One" />
<Button Grid.Row="1"
Grid.Column="0"
Text="Two First" />
<Button Grid.Row="1"
Grid.Column="1"
Text="Two Second" />
<Button Grid.Row="2"
Grid.Column="0"
Grid.ColumnSpan="2"
Text="Three" />
</Grid>