user110037: Can I import a 256 bit private key in a Wallet (binary format)?
Or do I have to convert it in another format?

user-1: dumpprivkey in bitcoin core returns private key in WIF
importprivkey adds a private key (as returned by dumpprivkey) to your wallet.
Private key to WIF: https://bitcoin.stackexchange.com/a/99101/

user26873: Most wallets (and by that, I mean almost all) will not accept a binary 256 bit private key, you will have to convert your 1's and 0's to a WIF format.
There are libraries in python and javascript (and I'm sure other languages too) available that can do this function conversion for you.

110037: <p>Can I import a 256 bit private key in a Wallet (binary format)?
Or do I have to convert it in another format?</p>
 -1: <p><code>dumpprivkey</code> in bitcoin core returns <a href="https://learnmeabitcoin.com/technical/private-key" rel="nofollow noreferrer">private key</a> in <a href="https://learnmeabitcoin.com/technical/wif" rel="nofollow noreferrer">WIF</a></p>
<p><code>importprivkey</code> <a href="https://bitcoincore.org/en/doc/0.20.0/rpc/wallet/importprivkey/" rel="nofollow noreferrer">adds a private key</a> (as returned by dumpprivkey) to your wallet.</p>
<p>Private key to WIF: <a href="https://bitcoin.stackexchange.com/a/99101/">https://bitcoin.stackexchange.com/a/99101/</a></p>
 26873: <p>Most wallets (and by that, I mean almost all) will not accept a binary 256 bit private key, you will have to convert your 1's and 0's to a WIF format.</p>
<p>There are libraries in python and javascript (and I'm sure other languages too) available that can do this function conversion for you.</p>
