thanks but the keys i have are extended private keys no wallet lets me import them

the old blockchain wallet from a few years ago let you save your pvt keys but was in base58 format example xprv9z3cKTxgg67knsZysV6cZ5HPTyCmk7UnpPmTpo4GC5YyreYK9rn3pBGKgjNgAxu5uirpe2p29t3 YffhuQ951YLgmvm94DNdoMpkPT2HqBJP

now step forward a few years there no wallets that let me import the keys i need a way to change about 400 base58 keys into a diffrent type of key so i can sweep or import all my old wallets theres 0.2 btc for anyone who can help me do this

i have about 100 pvt keys from a few old wallets how can i import them all in 1 go i tryed electrum but can only do 1 at a time the keys are in this format

xprv[mod edit: remainder of private key removed]