No, at least not currently.

The reason the passphrases are generated is so we don't have to worry about spending wallets with weak encryption that we or a hacker could crack if they ever gained access to our database.

But I think I was mostly biased against user-generated passwords because I'm sure some will pick weak ones and I'm not sure in what position this puts us. The obvious solution would be password rules but I was also biased against them because most of the times their UX sucks. But maybe our UX doesn't have to suck? Mhh

I also thought about PINs:

However, maybe a PIN chosen by the user would be even better?

Since we're trying to make it easy to unlock the wallets, and this is currently only possible by entering the passphrase, a user-chosen PIN should be even easier than entering a (custom) passphrase, right?

The issue with that is that encrypting the passphrase with a PIN for easy unlocking is very insecure unless the encrypted data is deleted after a few failed attempts. However, since the encrypted passphrase is stored in our database, we cannot actually enforce a limit on the number of attempts by anyone who has access to the database.

But as you can see, I don’t see how we could implement PINs without compromising too much on security.