So, here is my comprehension, pls correct me if needed:
* Starting at V23, creating a wallet would not allow the importprivkey command.
* If a blank wallet is created with V22 and importprivkey, this wallet can, subsequently be opened with V23 and up.
* It is not the Bitcoin Core version that prevent importprivkey, but the type of wallet created from the appropriate version.
You got it all correct.
Additionally, in v23.0, you can still create a legacy wallet by selecting the right options or disabling descriptor flag.
It's in v26.0 that it totally removed the option and the only way to create a legacy wallet is by using
deprecatedrpc=create_bdb config/arg.
But you must read the warning in v26.0 when loading a legacy wallet file.
Support for legacy wallet is scheduled to be dropped in v29.0:
https://github.com/bitcoin/bitcoin/issues/20160#issue-722711719So then, if "it's in the wallet" Does that mean that if a wallet is importprivkey compatible, then a user could importprivkey in V26.
In other words: Is importprivkey functionality stricktly dependent on the kind of wallet and not the Bicoin Core version ?
Yes.