GrapheneOS supports up to 128 character passwords to support using diceware passphrases. Using a strong passphrase avoids depending on the secure element. A random 6 digit PIN is secure due to the secure element rate limiting. Only a total of 20 attempts are permitted so even a random 4 digit PIN would be fine.
GrapheneOS adds the option to set a 2nd factor PIN for fingerprint unlock to make using a strong passphrase convenient without the downsides of biometric-only unlock.
Pattern lock strongly encouraging using only a tiny subset of the possibilities so it's much worse than your analysis shows. It was removed from GrapheneOS years ago because it's far worse than simply generating and using a random 6 digit PIN despite appearing to be similar. It gives a false sense of security and we didn't want to add support for a duress pattern or random pattern generating alongside those planned features. Built-in random PIN and passphrase generation is still in progress but has been started and will be shipped.
yep, human bias makes 4-digit pins and patterns a lot worse than the theoretical entropy, but still it's a decent starting point
my comment was about the decision of that person who deleted the comment to go for the pattern lock, while/because? 16 chars was supposedly bad for the password (although he/she has a point in that the limitation is annoying and counterproductive)
all of this i reckon was not criticism of GrapheneOS but stock Android, AFAIK grapheneOS's choices are all very sound
Thank you for your service.