If you want a _stacking_ wallet only (you don't plan to spend btc from this wallet for a decade), you can flip a coin 256 times or roll a dice, do some math to generate your seed.
Then import your extended public key to watch-only blue wallet (preferably connected to your own node).
That's all you need.
And stack
https://bitcoinmagazine.com/culture/diy-bitcoin-private-key-project
https://github.com/vicariousdrama/howto/blob/main/bitcoin/generating-device-seeds-using-dice.md