I would also like to know if it is possible to convert an extended private key in WIF format to xpriv. If so, what tool or code allows you to do this?
It is like asking if a leave can result to a tree. It is a tree that can result to leaves.
So that is not possible. I do not know how to explain this better than to tell you to read the mastering bitcoin chapter 4 which discussed about keys, addresses and wallet.
https://www.oreilly.com/library/view/mastering-bitcoin/9781491902639/ch04.htmlI think you haven't gotten my point yet, the point here is that it is possible to generate an HD wallet, that is, derive receiving and change addresses using a single WIF key as an HD seed, the only wallet that did this was Bitcoin Core.
According to this
post, Achow explains that in Bitcoin Core (bdb - legacy) the hdseed (WIF-key) is used to derive the extended private key (root master key) and then generate new keys using the new seed. Bitcoin Core used the BIP32 method to generate the master private key from a seed, the seed used was a WIF private key and not the common mnemonic in BIP39.
Today with the new descriptor format, this method is no longer necessary to derive an HD wallet using the WIF private key with the sethdseed command.
You answered your own question. It is used to set/restore the seed value for a Bitcoin Core HD wallet. The BIP32 Root WIF holds the 256-bit seed. It is not an extended key. The extended keys are derived from it.
I see, so why in the bitcoin core dumpfile, both the WIF key (which produces the keys from the WIF key seed value) and the xpriv master private key, but both generate the same keys?
I always thought that the WIF private key that contains the value hdseed=1 represented the same value as the xpriv, just converted to WIF.