Yep I'm sure they probably do use such apps to monitor you, which is why I'll never download one.
Did anyone watch that documentary about amazon a little while ago? Those echo things listen and record everything you say so amazon can monitor you. The couple they had on the documentary got in touch with amazon and were sent reams of paper with conversations that theyd had on. I believe the ones with cameras on are also able to watch everything you do. We've got both types and if it were down to me theyd be straight in the bin!