I heard the hardware wallet Ledger nano does support BTG. So if I buy a ledger nano would I be able to claim my BTG on there?
No. You would only be able to store BTG there. But not claim your BTG from your old wallet because there is no import option in Ledger Nano S.
You would need to import your private key in a BTG compatible wallet and then send your Bitcoin Gold to your Ledger Nano S wallet.
You can see which wallets suport BTG in their website:
https://bitcoingold.org/Not entirely true. You can use sweep function instead (this function is not available in native ledger app, but when you are using ledger with electrum this option is possible).
@OP You have been provided with instructions already. But if something is not clear, you can check my thread about BTG
https://bitcointalk.org/index.php?topic=2347158.0 Is there a way to claim BTG on ht tps://btgwallet.online/
My quick advice. Stay away. Better to use well established wallets ... too many scams around and this domain seems fishy to me ... one of the cheapest possible domains (if not free). Would you trust such service?