Use a Tox client for Android and F-Droid. Fdroid Classic it's better, it has a grid based layout which is easier to render on old devices. Install Braid for em

Use a Tox client for Android and F-Droid. Fdroid Classic it's better, it has a grid based layout which is easier to render on old devices. Install Braid for emergencies too. If some authoritiy ask, tell them you have Braid as a fallback on national disasters, because it works over Bluetooth too.