It’s hard to look at but any of the ones that are black squares in the picture would be the least used ones. It looks like that’s most any that starts in the 7000+ range.
4 digit pins are not secure. As long as you avoid all the light colored dots on the chart, that's the most secure you can make it.
If a system allows brute forcing without a pause, delay, cool down, or lockout, and a 4 digit pin is the only thing preventing access, they will get in.
Pin codes are great for quick access if you have a lockout mechanism after 3 failed attempts and it is impossible for an attacker to get the hashed code. It is only secure if you pick a pin that cannot be guessed in 3 attempts like your birthdate but that applies to any password.
Thats why they are used for credit cards, SIM cards or Bitlocker drive encryption. The hashed code never leaves the secure hardware so you cannot circumvent the lockout.
Even a 16digit numeric code, which I guess is the upper limit of what you can remember and quickly input, would take just a couple of days to brute force if the attacker does get hold of the hash.
Anecdotal but I've heard that when banks auto generate PINs for debit cards they filter out some suspicious ones like 0000 or 1234 because it only leads to customers complaining and wanting to change them (more work for the bank). Nowadays the customer can usually change them themselves, so it might be less true.
When I got my credit card (and credit account) set up, they had me set a pin then and there. But that might be because I had to create the account in person?