I am not sure on the terminology I should use to correctly ask my questions so don't read it too literally. This topic is about Ledger and Trezor hardware wallets.

I want to understand better how a hardware wallet works compared to a wallet like sparrow or electrum for example.

In sparrow and electrum wallet, the server will know all your public addresses that are inside your wallet.
Is it the same way with a hardware wallet? When I connect the hw wallet to a third party wallet, will the server know all the addresses that are inside my hw wallet?

What I think is confusing is that hw wallets can have more than just bitcoin. They can have other coins like eth and sol and many more. That means a server shouldn't be able to get all the addresses on the hw wallet.

I am guessing it might be that the third party wallet will automatically get all the hw wallet addresses for every blockchain, then it's up to the third party wallet how it has been built. The third party wallet could and it seems to be the standard, query all addresses at the same time. All Bitcoin addresses get sent to a bitcoin server, all eth addresses get sent to a eth node, etc, everything done at the same time.

But in theory there could be third party wallet that give you a choice to not query all addresses at the same time.

I have also read 2 things that seem contradicting. There is a popular scam where they sell used hw wallets after they have copied the seed phrase so they can recover it later when the new owner puts money into it. That's why they officially warn to never buy second hand hw wallets. But I've also read you can create new seed phrase and private keys. You can have several wallets inside the he wallet and switch between them so third party wallets will not know about the other wallets you have on the hw wallet. If that's possible then the scam threat isn't that serious if you just create a new seed phrase?

A friend asked me if she can just create a new address in her hw wallet, will it be secret address? Or is it likely coinanalys or some bitcoin server would be able to link that new address to all the other ones inside the hw wallet?