I am currently generating over 1T keys/day on one machine (in a low effort search for Satoshi’s keys). It’s totally doable if you have a full node and some code and can scale up a few AWS EC2 instances.

For brute forcing seeds, it’s a few more steps and it’s possible that they hid the coin in a deeper generated key—but he published the segwit address so it’s easy to just see if that shows up in the generated output. It’s also worth noting that the last word in a bip39 is a checksum so it has a reduced possible set of the full key words so really it’s not as hard as brute forcing a set of 4 words.

Actually in this instance, you don’t even need a full node. This can be done with just an offline machine looking for the hash address target.