Can I import a 256 bit private key in a Wallet (binary format)? Or do I have to convert it in another format?
It all depends on the wallet, sometimes it's not possible to directly import a private key, sometimes it uses some specific format (for example WIF for Bitcoin Core). I think you should be more specific or really we can't help much.– SosthèneSep 29, 2020 at 16:08
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/
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.