If you don't do this, then your wallet isn't permanently airgapped, since you've had to connect to the internet to download the app. If using Electrum like you suggest, then download the .apk to a computer, verify it, and then transfer to your phone via SD card.

I would argue that everyone who bought a Ledger is having a huge headache with the leak of their personal data and wish they had used an old mobile right now. If you encrypt your wallet on the device and encrypt the device (as most modern phones do automatically when you turn them off) the level of security is still more than adequate.

On the flip side, there has never been a proven remote attack against a Ledger device which did not require user error, such as someone signing a malicious transaction without paying attention to what they were doing. The whole point of a hardware wallet is that the computer you connect it to doesn't need to be airgapped - the private keys never leave the device. Although, given both the recent hack and Ledger's approach to it, I would definitely not recommend buying a Ledger. An airgapped cold storage set up is the best way to store your coins right now.