You need first to open the Ledger Wallet Chrome Bitcoin app,then click on My Account and Account Settings - Then under Extended public key click Export and you will get your public key.
Cool.
But what i get then is an 'extended public key'. When i put this really long key (longer than receive addresses eg) into any bitcoin gold blockchain explorer, it does not find anything. (I tried 3 different ones. I found stuff for my receive addresses, but no result at all for this extended key)
I think 'extended public key' is something different than public key?
It should work to my knowledge,when you get that extend private key from Ledger for BTC account you need to copy/paste that key in blockchain.info to check your BTC balance and transaction.
Check this public key : xpub/xpub6CUGRUonZSQ4TWtTMmzXdrXDtypWKiKrhko4egpiMZbpiaQL2jkwSB1icqYh2cfDfVxdx4df189oLKnC5fSwqPfgyP3hooxujYzAu3fDVmz
and this is how it should look when you enter them on blockchain.info :
https://blockchain.info/xpub/xpub6CUGRUonZSQ4TWtTMmzXdrXDtypWKiKrhko4egpiMZbpiaQL2jkwSB1icqYh2cfDfVxdx4df189oLKnC5fSwqPfgyP3hooxujYzAu3fDVmzMaybe problem is in format,just checked in Ledger and to work try to add xpub/ in front of public key.For every coin you want to do this you need follow same procedure and check on his blockexplorer.
You can also download Electrum and create watch only wallet.