That's a very nice guide indeed.

I never made one for me because I am too paranoid with security. I agree with Loycev,  turning off internet is not enough.

But I think I will make one for me 1bitmover .... Or a 3bitmover...

Sadly vanity gen doesn't work with segwit addresses
Nulius made this for generating a segwit vanity address. I never tested:
https://bitcointalk.org/index.php?topic=2934774.0