Make sure offline but would be fine.

Two things decide whether it holds up, more than "12 words, no passphrase": 1. Who can get the grid. If the grid (or the 12-word phrase that regenerates it) is ever found, your security is no longer 128 bits: it's whatever entropy your memorized pattern has. Patterns people can recall under stress ...

What is an emergency situation? I'm confused

What is "a passphrase generated grid?"

You sound like me… I’m rolling dice 12 and 24 word using jade for the 12 and 24 th word as just in case seed phrases. Not sure I’ll ever use them but I feel better having them ready.

A 12 word phrase carries 128 bits of entropy, and human chosen entropy is weak, so if you're generating anything yourself use dice rolls. For any realistic threat model, the physical security of that grid backup matters far more than the phrase length.

nostr:nprofile1qqsvlxe2zd56fnv3xf3ekyaw8ysq6upsgvte4q2wseywnef5pym7asgd3mz9l For a short stretch I'd be fine with it, if I had recovered from the grid and my pattern on a second device first. People draw guessable shapes, so I'd pick the cells with dice.

Emergency situation I'd probably opt for steghide.