The IRS is telling without telling you that it is FIFO or nightmare.

ive been researching it for almost a week now. i am practically a CPA now. this is not tax advice, but it appears to me that actual CPAs may have fucked over many, with some random shit from 2019 'guidance' called universal accounting. if you know your cost basis remaining already, and have it in a spreadsheet somewhere, assign it to your wallet(s) to match their current balance, and then you can use 'specific identity' of the 'tax lots' which in the future the exchange will need to know this info before you sell or they'll set it to zero/fifo.

I thought money was fungible. How exactly does FIFO work for money?

The IRS does not consider Bitcoin money. I do but they don’t.