Comparison in twig templates
{{ content }} is a render array, where you find the label of the key/label pair probably here:

{{ content.field_app_os[0]['#markup'] }}


But this is not ideal for logic:


The position in the render array can change, for example if you
install a layout module. 
The content of #markup depends on how the
field formatter is configured in the view mode.
The label is translatable, so the
logic breaks on a multilingual site.


So it's better to use the database value in:

{{ node.field_app_os.value }}


This is the first part of the key/label pair, which is untranslatable and you can access the value independent on how the field is configured in the view mode.