I don't have any android phone so I can't use coinomi wallet.
Is there any BTG wallet that let me import my private key from electrum?
Using the original BTG client. But since this one was also compromised by hacker I don't find it as a best solution. You would also need to download entire blockchain.
Aternatively you can use some android emulator.
Is there a lightweight client like ElectronCash? Strange nobody developed it yet...