I agree with Razem, if you turn off Wi-Fi and mobile data you’ll be pretty safe.
Bear in mind also, that alternative operating systems (not too different in basic manipulation from what you already have) are available and will continue to be updated, so you might consider moving. I appreciate you’ll probably not want to do it yourself, but someone you know might be able to help, or maybe a Fairphone Angel if there’s one nearby (more info here).