You don’t need to be connected to a grin node or anything to use account creation in grin-wallet, which was moved to separate files. You could get a rasb pi, github clone, build, disconnect, create account, wipe the pi, you’re done. Account creation just is storing files in the .grin folder. It’s actually just a common 24-word key - that is the grin private key/address. Same as all these other coins with the 12-word mnemonic phrase, your standard BIP39 128bit security key (except grin is 24-words of the BIP39 word list or 256bit) https://en.bitcoin.it/wiki/Seed_phrase The software for setting these up has nothing to do with grin.
As a total aside, I find it disturbing that there are only 128bits with these keys, and bitcoin and everyone has one. It seems like collisions are really likely, especially with 1000s of coins using the same system. Grin is better than that, with a 24-word seed phrase, which I find comforting. But you can restore your wallet from your BIP39, and you can make your BIP39 without being connected.
See here https://en.bitcoin.it/wiki/Seed_phrase where you initialize the wallet and get the seed before connecting to a node or anything (which follows). It is the exact same as a bitcoin paper wallet, which is just a private key and a public address, grin is just private key, as grin has no public addresses!