Inquiry Regarding Bitcoin Core

-del

Why don't you use dumpwallet in Bitcoin Core itself? That sounds a lot like trusting third parties. Wouldn't Electrum be a better option to import your keys (or watch-only addresses)? If downloading 600 GB is a problem, maybe you can find someone to ship you a disk with the full blockchain. Verify it after receiving and it's as good as downloading it yourself.

Yes, Bitcoin Core v0.21.0 (released on 2021) introduce new wallet format which use SQLite backend. FYI, you can use certain RPC call on your wallet.dat file without downloading the blockchain. If you use the GUI application, you can disable the network activity by clicking icon on bottom right and choose "Disable network activity".

I know a few of them I haven't tested them yet just found them when looking for a free server that can use API RPC calls, you don't need to download the whole blockchain and it supports RPC API calls free with higher limit calls. The only problem is I don't know if you can use it on wallets. What exactly do you want to do with RPC calls? To recover your wallet? Like they said why trust 3rd party it's risky once you use a 3rd party service your wallet is not safe anymore. Anyway, here's the link - quicknode.com - chainstack.com

If hard drive space is your concern I can help with that.  I have a 2TB Seagate spinner that's just taking up space in my desk drawer.  If you're in the US I can ship it to you, I'd rather see it get used than go to a landfill. To get the master private key you can use the dumpwallet command in the BitcoinQT's console.  Like others have mentioned, using a third party is not advisable especially for your use case.  You would be exposing your wallet to an anonymous server, compromising your security. If the server is hosted by someone who's trustworthy they most definitely have wallet RPC commands disabled.  If they don't, they're not trustworthy.

I could copy the block chain onto the drive before I send it to you, that's not a big deal.  I'm traveling at the moment and won't be home until Tuesday, but let me know if you want it and I'll get started on it next week. Yeah, as long as your pruned node is synced with the wallet you don't need the whole blockchain. Unfortunately (or fortunately, depending on your take on the issue,) no.  That feature was disabled for new wallets from a few versions back (taproot implementation, I think.)  Using hdseeds to back up and restore wallets wasn't a great idea to begin with, so the dumpwallet command was obsoleted.  Here's an explanation by one of the bitcoin developers as to why it wasn't a good thing to do: https://bitcointalk.org/index.php?topic=5215266.msg53539363#msg53539363 You can still dump the private key of any specific addresses, though.

Yes. AFAIK no, but you can use listdescriptor true to get descriptor which represent extended private key.

That's correct. Also, ABCbits reminded me; the master private keys of new wallets can be exported by using listdescriptors true.  The keys displayed by that command are the ones from which all keys are derived.

For descriptor wallets, you cannot export single private keys, but you can export the descriptor that contains the BIP32 extended private key from which the private keys are derived, for this you can use the command: listdescriptors true passphrase will be requested. You will see the output descriptors containing the descriptors with the receiving and change addresses. Read more details in this topic. If you want to view the extended public keys of the wallet, just type listdescriptors without the true argument. To import descriptors into a bitcoin core descriptor wallet, see this topic.