There are programs that overwrite your harddisk with random data, cluster by cluster. I've needed one long ago for Windows, I don't know what you use, but I'm sure a search will help you out. That should be pretty safe.
Another idea would be to make on the new laptop completely new wallets for the crypto you've used and transfer your coins to the new wallets. Of course, you'll also need to change the passwords and 2FA for all the accounts if you are this paranoid.
But I think that proper full overwrite should do.
Another idea would be to make on the new laptop completely new wallets for the crypto you've used and transfer your coins to the new wallets. Of course, you'll also need to change the passwords and 2FA for all the accounts if you are this paranoid.
But I think that proper full overwrite should do.Transferring the coins to a new wallet would seem to be the best option if one is really "paranoid" that deleted data can still be recovered using new technologies or tactics. I really understand the concern of OP because as they are saying nobody can really be too careful. Another good option is never to sell the laptop or just keep it which is for sure make things really so safe.
I already told my friend I would sell it when the new one arrives, I trust that he wouldn't go snooping around anyway but I'd probably go for a combination of moving to a new wallet + wiping thoroughly with multiple software options.