Molly - I use Signal Cli as my "main" Signal client and connect Molly to it and it works perfectly. I especially love that the Accrescent version is completely FOSS and gets notifications via Molly Socket. I find the battery drain to not be that different from using SIgnal which gets its notifications via Google's Firebase.
Exif-eraser - The GrapheneOS camera and screenshot feature already erases exif data so I'm not sure if the app makes any difference to be honest. I do like the fact that it randomizes the file name though.
Cryptomator - Works perfectly, the best way to encrypt files and folders on Android. You do have to pay for a licence key though. However it does go on sale throughout the year; you can follow their Mastodon account to check out when it does.
Never used IVPN.