I have heard of the Glacier protocol (
https://glacierprotocol.org/) for storing bitcoins in cold storage which involves a couple laptops and USB sticks. I don't know how secure it is though, because I have never tried it (and most people here aren't in a position to order $1200 worth of computer equipment just for this task since it requires factory-restored devices).
There were rumors that if you make a transaction using the same address you use to conduct a transaction, it would mean your public key will b exposed and that a quantum computer might just be a threat and can also expose your private key. not sure if it's possible but store your coins and not use the wallet afterward. not even once.
They are not rumors. They are real.
Right now I can download Pollard's Kangaroo program from Github and use it to break private keys searched in small (<60) ranges. A cluster of several dozen GPUs can break private keys with ranges as high as 115 bits.
Actually the public key isn't even needed, the same GPU clusters can theoretically brute-force RIPEMD160 hashes (ie. your address) with smaller-sized ranges.
There are a lot of tools for offline generation of paper wallet. You could even disable internet on you computer to do is safier. Or use one-time VM for generation of keys
Paper wallets are complicated to set up and too easy to make a mistake while printing/engraving the private key. What happens after that is you forget or lose a couple characters of the private key.
Paper wallet generator sites have never been secure (cf. BitcoinPaperWallet) and you never know when or if they'll be sold to somebody malicious.